Can I change who "ME" is?

Answer 1

You can do this by:

1. exporting your family tree as a GEDCOM file
2. creating a new family tree from your account page
3. importing your GEDCOM file
4. as a last step it asks you who the main person should be

Note that photos are not exported with your GEDCOM file, and you'll have to reshare the tree with anyone else who has viewing or editing rights.

I believe that you could also do it this way, but I haven't tested this:

1. Click on the person you want to make the main person
2. Mark them as living if they are not
3. Share the tree with them (give them editing rights)
4. Copy the URL toward the bottom and paste it into another browser
5. Create a new account so you can edit everyone in the tree. 
6. Close your old account after you're sure everything is working.

This should preserve the photos, but you'll have a new account. If you only have one family tree in your account, and you are the only one editing the tree, that's maybe not such a big deal.