Issue Description
I need my plans to be dimensioned using the Imperial system, but every time I modify the dimensions in the Project Preferences, it goes back to Metric whenever I switch between drawings.
Solution
Dimensioning is part of the View Settings so every time you modify the drawing, you need to redefine the current view or manually set it in the View Settings.
1: Go to Options > Project Preferences > Dimensions
2: If you need a new dimensioning type that differs from the existing ones, you can create by storing it in a different Name. Alternatively, you can modify an existing one by using the same name to overwrite it.
Click OK to confirm.
3: In the Navigator, go to the View Map of your drawing. Right-click on the view you’re adjusting and select "View Settings."
4: In the "Dimensioning" section under 2D/3D Documents, select the modified or newly created dimensioning type. Click OK to save your changes.