Numbering and bullet formats are stored in a separate file called ListGal.dat. I'm not sure if that applies to picture bullets as well, but you can try deleting ListGal.dat and see if it resets the options in the Picture Bullet dialog box.

Do the following: Exit Word. You will find ListGal.dat in your Windows user profile path. You can search for the file, but you must display hidden files and folders first. Delete it once you have found it, and then restart Word.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional