I don’t receive mail from my primary alias

I originally had my primary alias set to my Yahoo! account, but I would never receive emails through the mail app. My Gmail account worked perfectly, so I assumed that it had something to do with the fact that I rarely even use the Yahoo account, and probably just hadn't remembered the password correctly or something. But when I tried to re-sync it so that I'd actually get emails, it wouldn't let me change anything, so I renamed my primary alias to the Gmail account, assuming that because I actually knew the account information, it would sync properly, and I'd continue getting mail. Instead, the Gmail account stopped working, even though the Yahoo email works fine now that it's only a secondary alias. What am I doing wrong? Do I just need to get Outlook? Because no offense, but I'd rather not add another email to the list.