If you are primarily a command line user in Linux, then it is possible that you don’t use the mouse a whole lot. If you use a desktop environment such as KDE or Gnome, and use the graphical file managers then you probably use the mouse quite a bit. The common practice is to click on file icons (or file names) to open the files in appropriate software.
It is possible to configure precisely how mouse clicks work in desktop environments such as KDE (also Gnome and other DE). We will see how left mouse clicks (or right clicks if your left handed) can be configured in KDE. As everybody knows, there are two different types of clicks: single and double.
As with most other configuration in KDE, the System Settings utility is the place to configure the mouse as well. Open System Settings from either the KDE start menu or by executing the command systemsettings from the command prompt.
In the utility, click on Input Devices under the Hardware section in System settings. Now click on the Mouse section in the left hand side menu.
The options here should be pretty straight forward. If you want the first or single click to select the icon and the double click to open the files (or folders), then you select the first option that says the same: Double-click to open files and folders.
If you want the single click to open files then you select the next option instead: Single-click to open files and folders. You can configure couple of extra features if you select this option. One issue with selecting this option is that there is not clear-cut way to just select the icon by using the mouse (with out opening the file) any more. However, you can configure the hover to work as icon selection. You can configure the icon to be automatically selected after a specified delay.
The Advanced tab on this screen gives you some extra options to configure the other properties of your mouse. The Pointer acceleration allows you to configure how fast you want the mouse to move. A value of 2x is usually optimum, 3x can make the mouse pointer difficult to control while 1x can be excruciatingly slow.
Another important configuration is the Double click interval. This determines as to how fast you need to click to generate a double click event. If the time between two clicks is more than this specified value, then they are considered as two separate single clicks. A value of 400ms or 500ms is optimum for this in most cases. If you find yourself clicking repeatedly and the files not opening, then this value is too small for your system. Increase the amount in increments of 100ms to find the optimum that works for you.