What is the correct term for "tense" of a pronoun?

A bit of background to explain my question:

I left a complimentary comment about/to the creator of a youtube video "[subject] is great. I like his book."

In general, I mean the comment to speak to everybody else viewing.

However, he could be reading the comments. I do mean it as a compliment, and if were speaking directly to(at?) him, I would say "I like your book."

I'm curious/confused about using the wrong word "tense" of pronoun, but tense isn't the right word, that's verbs only.

Is this a "pronoun" / "direction" issue? I want to read about whatever this is called, but I can't quite pin down what my issue is. Is it even a pronoun, is that the right term?

And then from that, Which would be the better case to address a comment? That's my real question. Is there an internet comment etiquette subreddit? ;)

I appreciate any comments, I really like thinking about semantics