This seems like it should be so easy, but I can’t figure it out. I have two email accounts. I just had to delete and re-add my main account and now it shows as the second account in the left sidebar. I just want to drag the account up so it’s first, but it won’t let me do that. Is there a way to just move it to the top? 
Go to menu/tools/accounts. In the left pane, highlight the account you wish to move up and click on the up-arrow until it is at the top.
You’re the best! Thanks 