Meaning of "quite" in "I don't quite understand/know/remember, etc."

Hi:

How are you all? I hope you all will be fine. I'd like to ask what "quite" means in clauses like "I don't quite understand...", I think I don't quite know...", "She doesn't quite remember...", etc.

Does it mean, "I don't fully/completely understand/know/remember..."?

Thank you all!