Maybe you already found out how to change your email address, but.. I'll post this for just in case.
If you are using the app, it seems you cannot change these info.
So, go to the ebay website, and you can see Hi ***(your name) on the left side and above the letter of "ebay".
Click your name, go to Account settings. Find "Personal Information" under "My eBay Views".
Then finally, you can change any other information in this page.
Hope this will help you and.. good luck!
