Pointers and Paint Tools
This option has no effect unless Show pointer for paint tools is checked. If it is, you have three choices: Tool icon, which causes a small iconic representation of the currently active tool to be shown beside the cursor; Tool icon with crosshair, which shows the icon as well as a crosshair indicating the center of the cursor; or Crosshair only.
This option decides the direction of the pointer. The default is Right-handed. When Left-handed is chosen, the pointer is flipped horizontally.
If this option is checked, then when you use a paint tool, the outline of the brush will be shown on the image as you move the pointer around. On slow systems, if the brush is very large, this could occasionally cause some lag in GIMP's ability to follow your movements: if so, switching this off might help. Otherwise, you will probably find it quite useful.
If this is checked, a cursor will be shown. This is in addition to the brush outline, if the brush outline is being shown. The type of cursor is determined by the next option.
Extended Input Devices
When enabled, the same tool and tool options will be used for all input devices. No tool switching will occur when the input device changes.
This large button allows you to set the devices associated with your computer: tablet, MIDI keyboard, etc. If you have a tablet, you will see a dialog like this:
When you check this box, GIMP remembers the tool, color, pattern, and brush you were using the last time you quit.
Självförklarande.
Delete your settings and restore default settings.