Hi there fsiaccounting-fr,
Thanks for reaching out about connecting an app. QuickBooks Online is a great tool able to assist you in keeping track of sales and expenses so you can see the profit of your business. I can provide some assistance with being unable to connect to an app.
If you're trying to sign into the QuickBooks Online mobile app as a newly appointed primary admin but get an error signing in, then one possible cause would be app data. These temporary files can affect the navigation within the app, and previous data can have an effect on login. The way to remove app data would be to delete the app from the device in question and install it once more from the app store once more.
If you have any other questions or need further assistance, feel free to reach out here.
