I have had my Mturk account for many years. I used it for the first 2 years or so then I forgot all about it because, being outside the US, I wasn't able to get paid other than giftcards.
This is not the case now. So I am back.
Long story short, I am learning about a few places (such as this) for reviews, etc, and I am slowly learning to use them.
On my profile, I have 'reviews' and 'return reviews'. What are return reviews, please?
Also, I can see that I can change my profile image here in the forums, but I didn't see an option in the main site. How do I do that?
Not sure where you are seeing "Reviews" and "Return Reviews", but typically a return review is someone leaving a review without submitting the HIT. For example, if the HIT has a screener, they leave a review to inform others, but they do not submit the HIT.
When you review something, you have completed the HIT and now you are writing your review to tell others of your experience.