You've come to the right place, @letitia.berbaum.
I can help you ensure to login to the correct QuickBooks Online account using your mobile app. Let's get started.
Firs,t let's ensure to download the correct mobile app. Depending on the mobile device you're using, here's where you can download the QuickBooks Online mobile app:
Lastly, let's make sure to use the same username and password when accessing your account in both the regular browser and the mobile app.
For visual references, you may check this short video clip:
Keep me posted if you have other questions. I'm always here to help.