Technically, reinstalling the app should help fix the login issue you're experiencing by clearing the data stored on your mobile device. Since it didn't resolve the unexpected hitch, I'd recommend getting in touch our Online Support Team.
There they can check your account information and provide you with additional workarounds for you to use the QBO app without any issues. In the meantime, you can use a regular browser to access your QuickBooks Online account.
Please feel free to update me how this goes, Kellyjohnsson83. I'm here if you need further assistance.