I signed up using google, so I can't change the password for some reason.

the subject states it

Even if you sign up with Google it should still allow you to change your password. Please refer to the following article that explains How-to-reset-the-password. 

This could also be related to your browser cache. Please clear it once and then re-try resetting the password. If the article doesn't help please let us know what error you get? You can even Post-Screenshots-to-Our-Support-Forum. 

Let us know how it goes.