Incorrect monogram initials displayed on Apple Watch face

Open Watch app in your iPhone, enter Monogram in the search box, and check what is shown for the Monogram setting.

Does that differ from what is shown on the Watch face, where the face even shows the monogram?

If so, check for watchOS updates, restart, and test again.

If you have contacts in iphone Settings, Apps, Contacts set to display as Last,First your monogram will be reversed, maybe that is your problem

You have told us absolutely nothing about your scenario. We don’t know what you tried, what you saw, what worked, what failed, error messages, where these monograms originate, Apple Watch model, paired iPhone model, watchOS version, iOS version, etc.