How do you change the monogram?

If you go to the Watch App on the iPhone, go to Clock, then Monogram and I was able to use 3 characters. Looking at the information below Monogram, you can choose up to five characters to appear in the Monogram complication on the Typograph, Infograph, Meridian, California, and Color Watch faces..

As indicated when you make feedback, Apple reads all but does not provide individual feedback. Just because you made a suggestion and it was not implemented, does not mean that leaving feedback is not a good idea. Apple cannot make all changes that users recommend, but does not mean it may not at a different time, and after a large number of people suggest it.

Take care.

For that, you would need to make a suggestion to Apple, which is done on their feedback page. Go to www.apple.com/feedback/watch.html