Software preferences allow a user to save optional settings for how an application is used. The preference settings that are made will remain for future work with the software. The preferences that are available will vary from program to program. Sometimes there are many, other times only a few. The more preference settings that are available, the more the user will be able to customize and improve their user experience.
Photoshop has many preferences.
The following instructions are for setting some of the preferences in Photoshop CC. The preferences that are available are the same in Macs and Windows.
Windows: Edit > Preferences
Mac: Photoshop menu > Preferences
In the Preferences dialog:
Disable (uncheck) Use Rich Tooltips
These are the pop-ups with information about a tool...
They are usually more of an irritant than a benefit.
Disable (uncheck) Use Shift Key for Tool Switch
Doing this will allow you to use a single keyboard key to select a tool and not require you to use the Shift key in addition to the tool's letter key.
Enable (check) Overscroll
Doing this allows you to use the space bar-click-drag or the hand tool to move an image around when it is fully seen. This is helpful when shapes go beyond the edges of the visible image.
Units and rulers >
Rulers > Pixels
Type > Pixels
Generator > enable (check) Generator
Note that there are also preferences to be set in Adobe Bridge and Adobe's Camera Raw plug-in.