Just a question, when the number under the achievement is green does that mean I have completed it? Might be a stupid question but just curious xD

[edit] So I actually was on the "quest" section of achievements and saw like for example I had no pete's quests completed. Then we I clicked on it and went back it said I had like 400/500 completed and all the seconds except the last 3 were green. As I scrolled down more achievements were green and I know I had not completed them. Is this a known glitch?

Yes, when it's green it means that you've completed it.

If you haven't been around since they revamped the achievements, it may have retroactively given back some that you had before. If you don't think that's the case, then try filing a ticket and someone there should be able to help you get it sorted.