GFF has many ways for you to customize its environment. This is the menu that opens when you click on the Settings tab. While Refresh is self explaining other choices need some introduction. In general, the tick mark indicates that this is the choice that has been made by you or the program. You can save your choices under the File menu with Preferences → Save Preferences and Preferences → Load Preferences.

Fretspacing even Left Handed Add Capo
Color Settings Sound Settings Sharps/Flats/Notes
Show/Hide Numbers Show/Hide Stave Scales and Modes
Retune Guitar Show/Hide Tuner