Toolbar / Icon:
Menu: Edit > Application Preferences
Shortcut: Ctrl+, (Mac: ⌘,)
Commands: preferences
In the application preferences dialog, you can adjust the look and behavior
of QCAD and its tools and graphics views.
QCAD also stores some of these settings inside the drawings. Those
settings can be changed in the application preferences as default settings for
new drawings. In other words, they don't affect existing drawings but only
drawings that are created after the preferences have been changed.