By: David Blatner
July 12 2007 • 3:53 PM
InDesign Measurements Changing Unexpectedly
James wrote:
Can you tell me why InDesign sometimes decides to change all the measurements (for space before/after/etc) from ‘mm’ to ‘pt’!? I have to keep opening the preferences and manually change them back again!
This one really stumped me until Anne-Marie reminded me that there’s a keyboard shortcut for changing the units of measurements: Command-Option-Shift-U (or Ctrl+Alt+Shift+U on Windows). Each time you press this, you cycle through the measurement systems: points, picas, inches, inches decimal, millimeters, centimeters, ciceros, agates (in CS3), and Custom.
We checked it out with James, and he replied: “That’s it!” Apparently he was trying to underline text with a KBSC from time to time and was adding the Option/Alt key accidentally. Well, we all learned/remembered something today. 
Another reason it may change is because of a script. If you run the script “corner effects” (to change just one corner) it will change all of your units to points unless you type in a different measurement.
Don’t forget you can right-click on the rulers too to change the units of measurements.
Don’t forget, also, that you can simply type in “in”, “pt”, etc after your value to enter measurements in the system you prefer - regardless of what is set in Preferences.
Thanks for the ‘other’ solution, Fritz. I also have my units change on me occasionally, but the first answer here didn’t explain the issue for me. Your ’script’ suggestion solves my problem.