The switches editor, available through the menu Project->Edit
Switches, lists all the source files associated with the selected
project.
For each file, the compiler switches are listed. These switches are displayed in gray if they are the default switches defined at the project level (see The Project Properties Editor). They are defined in black if they are specific to a given file.
Double-clicking in the switches column allows you to edit the switches
for a specific file. It is possible to edit the switches for multiple
files at the same time by selecting them before displaying the contextual
menu (Edit switches for all selected files).
When you double-click in one of the columns that contain the switches, a new dialog is opened that allows you to edit the switches specific to the selected files.
This dialog has a button titled Revert. Clicking on this button
will cancel any file-specific switch, and revert to the default
switches defined at the project level.