RESTRICT EDITING IS GREYED OUT. I CAN NOT START ENFORCING

When Restrict Editing and Start Enforcing Protection are greyed out, Word is not in a state where it can apply new editing restrictions. This is typically due to how the file is opened or shared.

Try these steps in order:

1. Confirm the document is not opening as read-only

• Go to File > Info.
• Select Protect Document.
• If Always Open Read-Only or Always Open View-Only is enabled, select it once to clear it.
• Close and reopen the document, then check Review > Protect > Restrict Editing again.

2. Switch the document to Editing mode

• In the upper-right corner of the Word window, find the mode selector (it may show Viewing or Reviewing).
• Change it to Editing.
• Return to Review > Protect > Restrict Editing and see if Yes, Start Enforcing Protection is now available.

3. Check if the file was shared as read-only

• If the file was shared as read-only, close it and open it again.
• When prompted, choose No to open in editing mode instead of read-only.
• Then set up protection:
  1. Go to Review > Protect > Restrict Editing.
  2. Under Editing restrictions, select Allow only this type of editing in the document and choose the restriction type (for example, No changes (Read only)).
  3. Select Yes, Start Enforcing Protection and add a password if desired.

If the document is controlled by Information Rights Management (IRM) or by organization policies, or if the license is not active, protection options can remain disabled and cannot be changed until those conditions are resolved.

References:

• Enable editing in your document
• Make a document read only in Word
• Allow changes to parts of a protected Word document
• How to apply permissions for the Editing Restrictions feature in Word 2003
• I can't edit my word doc. - Microsoft Q&A
• Why is Word 2024 opening .docx files in Viewing/Read-only mode? - Microsoft Q&A