Configuring Dolphin
Dolphin distinguishes two different kinds of settings:
Settings which affect the general behavior of Dolphin. These can be configured using the Preferences Dialog.
Settings which determine how the contents of a folder are displayed in Dolphin. These settings are called View Properties and can be controlled with toolbar buttons, via the View menu, and with the View Properties Dialog. In the default configuration, the view properties are remembered for each folder, but Dolphin can also be configured to use common view properties for all folders in the General section of the settings.

The Dolphin Preferences Dialog
The Preferences Dialog is opened via Settings Configure Dolphin... in the menu in Dolphin's main window. The settings are divided into several groups which can be accessed by clicking the corresponding icon on the left of the dialog.

Startup
This group contains settings which control the appearance of Dolphin on startup.
Screenshot of the Startup settings in Dolphin's preferences dialog
Startup Settings.
Startup Settings in Dolphin's Preferences Dialog.
The Home Folder is the folder which is opened on startup. The location of the folder can be entered directly or chosen in a dialog which can be opened by clicking the button showing a folder icon. Moreover, the current location or the default location (which is the user's home folder) can be used as the Home Folder by clicking the corresponding button.
Split View Mode controls if the Dolphin view is split on startup or not.
Editable location bar controls if the location bar is in editable mode on startup. The bread crumb mode of the location bar is used otherwise. See the section about the location bar for details about the two modes.
If Show full path inside location bar is enabled, the full path of the current location is shown in the bread crumb mode of the location bar. Otherwise, a shortened version of the path is shown if it begins with the path of one of the places in the Places panel.
Show filter bar controls if the filter bar is shown on startup or not. See the section on the filter bar for details.

View Modes
This group contains settings which control the behavior of Dolphin's view modes. The three view modes (Icons, Details, and Columns) are accessible via the tab bar on top.
Screenshot of the Icons View settings in Dolphin's preferences dialog
View Modes Settings.
View Modes Settings in Dolphin's Preferences Dialog.

Common settings for all view modes
All three view modes have some common settings:
Sliders which control the size of the icons. The Default or Preview sizes are used if previews are disabled or enabled, respectively. Note that the icon size can be changed easily with the zoom slider in the status bar if the corresponding option is enabled in the General section of the settings.
A setting for the font used in the view mode: either the system font or a custom font can be chosen.
The settings which apply to only one of the view modes are discussed below.

Icons
Besides the common settings of all view modes, the icons view has the following settings:
In the Text section:
Number of lines is the number of lines of text which appear next to the icons. If the name of a file or folder is too long to fit into the chosen number of lines, it will be abbreviated, and ... will be added at the end.
Text Width controls the maximum width that is reserved for the text of a file item.
In the Grid section:
If Arrangement is set to Rows or Columns, the items will be arranged in rows from left to right or in columns from top to bottom, respectively.
Grid spacing controls how far the items are apart in the view.

Details
Besides the common settings of all view modes, the details view has only one setting:
If Expandable Folders is enabled, the details view can show the contents of all subfolders of the current folder as a tree. A branch of the tree can be expanded or collapsed by clicking the + or - button next to each subfolder.

Columns
Besides the common settings of all view modes, the columns view has only one setting:
The Text Width setting controls the width of each column in the view.

Navigation
This group contains settings which control how navigation in the folder structure and in archives works.
Screenshot of the Navigation settings in Dolphin's preferences dialog
Navigation Settings.
Navigation Settings in Dolphin's Preferences Dialog.
Dolphin can be configured to open items with a single mouse click (Single-click to open files and folders) or a double mouse click (Double-click to open files and folders). In the latter case, a single mouse click will select the file or folder.
Archives will be opened inside Dolphin, and not in an external application, if Open Archives as folder is enabled.
If Open folders during drag operations is enabled, dragging an item with the mouse and hovering a folder with it for a short time will open that folder. This permits to move or copy items quickly to folders which are several levels deeper in the folder hierarchy.

Services
This group offers a selection of services that can be shown in the Actions submenu of Dolphin's context menu which appears when clicking a file or folder with the .

Trash
This group contains settings which control the behavior of the trash.
Screenshot of the Trash settings in Dolphin's preferences dialog
Trash Settings.
Trash Settings in Dolphin's Preferences Dialog.
Files which are older than a configurable number of days can be deleted automatically.
The size of the trash can be limited to a configurable percentage of the disk size. If this limit is reached, a warning can be issued, or the oldest or largest files can be deleted automatically.

General
This group contains settings which control the general behavior of Dolphin. The group is divided further into four subgroups which can be accessed using the tab bar on top.
Screenshot of the General settings in Dolphin's preferences dialog
General Settings.
General Settings in Dolphin's Preferences Dialog.

Behavior Tab
In the View Properties section, it can be configured if the view properties are stored for each folder or if common view properties are to be used for all folders.
In the Ask for Confirmation When section, warning dialogs which are shown before potentially harmful actions can be enabled.
If Rename Inline is enabled, no dialog asking for a new file name will be opened when renaming a file or folder. Instead, the name can be edited directly inside the view.
When hovering a file or folder with the mouse, a small window with information about it is shown next to it if Show tooltips is enabled.
Show selection marker shows a small + or - button above an item's icon if the item is hovered with the mouse. These can be used to select or deselect the item.
Natural sorting of items controls how items are sorted in the view. If this option is enabled, the sort order of three example files will be
File1,
File2,
File10.
If this option is disabled, the normal alphabetical sorting will be used, which leads to the sort order
File1,
File10,
File2.

Previews Tab
In this tab, it can be configured for which file types previews are shown. Moreover, the maximum filesize for which previews are generated can be chosen, and it can be configured if thumbnails embedded in files are used or not.
If previews are enabled for folders, previews of some files in the folder will be shown inside a folder's icon.

Context Menu Tab
In this tab, it can be chosen if the Delete, Copy To, and Move To commands are shown in the context menu which appears when right-clicking a file or folder.

Status Bar Tab
In this tab, some additional items can be enabled for the status bar, provided the status bar is wide enough:
A zoom slider which can be used to change the icon size quickly.
A bar that shows how much space is free on the current drive.

Folder View Properties
The following settings control how the contents of a folder are displayed in the Dolphin view, and are stored on a per-folder basis by default:
The view mode (Icons, Details, Columns)
The sorting of items, which is determined by the sort order (ascending, descending) and the attribute (such as name, size,...) that the items are sorted by
Sorting of folders and files – are folders shown first or not?
Previews – are they shown instead of icons (based on the settings made in Previews tab of Dolphin's General settings) or not?
Are items shown in groups in the Icons view?
Are hidden files shown?
What additional information (besides the name) is shown in the Icons or Details view?
The view properties can be configured in the View menu, some (such as the view mode) can also be changed using toolbar buttons.

The View Properties Dialog
Screenshot of the View Properties dialog
The View Properties dialog.
The View Properties Dialog.
The View Properties dialog can be used to quickly modify several view properties at once. This is done for the current folder, for the current folder including all subfolders, or even for all folders, depending on the choice made in the Apply View Properties To section.
If Use as default for new folders is enabled, the chosen view properties will also be used for all folders which do not have customized view properties yet.