Thank you Diego and Westley.
This is the UI action I'm trying to do with code:
1. Open Sales Order form -> Go to Tools > Customization Tools > Settings -> Uncheck the 'Visible' checkbox for all the UDFs.
2. Repeat this for all Marketing Documents forms except Sales Quotation.
3. Copy form settings from my user account to all users so they don't see these fields.
What you proposed would work, but is there a one time solution out there without manipulating the form every time users open them?
Thanks,
Grace