Changing the units in Preferences won't change anything if your document is set up in another unit of measurement. It will work when creating new files but if you're working with a file that was created by someone else or before you switched your preferences, it will revert back to the native document settings. If this happens, open up the file that you want to change the units of measurement in and go to File > Document Setup, change "Units" to your preference, hit "OK" and then save the file before closing. It looks like document setup overrides preferences, which makes sense. Hope this helps everyone.
Changing the units in Preferences won't change anything if your document is set up in another unit of measurement. It will work when creating new files but if you're working with a file that was created by someone else or before you switched your preferences, it will revert back to the native document settings. If this happens, open up the file that you want to change the units of measurement in and go to File > Document Setup, change "Units" to your preference, hit "OK" and then save the file before closing. It looks like document setup overrides preferences, which makes sense. Hope this helps everyone.