There are several very different ways of getting to Units Settings in the Revit User Interface. Most of them are not very intuitive – and certainly they are totally different from each other.
Project Unit Settings
There are 3 different icons on the ‘Manage’ ribbon, depending on your screen resolution and size:
 |
| Largest resolution or screen |
If you are operating on a laptop or low resolution, the icon automatically reduces in size, and you may or may not get a text description:
 |
| Medium resolution or screen |
 |
| Smallest resolution or screen |
Once you click on the Project Units icon it takes you to the units dialog box, which has a list of different kinds of units:
Once you choose a particular unit type, it gives the project-wide ‘Format’ settings for that type. Since this is the project settings, the checkbox at the top is greyed out. Some of the checkboxes are related only to imperial measurements so would always be greyed out for metric users.
This dialog box is the one…