Text formatting

Here is a customer that encountered the same or a very similar problem. It was resolved for them with the latest release:
https://community.adobe.com/t5/premiere-pro-bugs/unable-to-change-color-to-the-part-of-the-text/idi-p/13765400
Is it possibly resolved for you as well now? And yes, like @Stan Jones said, please include a screenshot if the problem is still happening for you.

Brent,

You must select just the word you want, then apply the bold (or italics etc). If that doesn't work, please post a screenshot.

Are you applying a "style" by any chance?

Stan