Does anyone know why my usual login details (used for a year on an iphone) don’t work when I try to login to the intuit quickbooks app on my new fairphone 3?

I can help you open your account using the new fairphone 3, @nancy67.

This error usually happens when the incorrect link or app is installed. To narrow down the cause of this error, you can start by uninstalling the current app. Then, install the QuickBooks Self-Employed (QBSE) app using the correct links. 

Here are the following:

• (Android)   https://play.google.com/store/apps/details?id=com.intuit.qbse&hl=en  
• (IOS)  https://itunes.apple.com/us/app/quickbooks-self-employed-mobile/id898076976?mt=8 

Once done, try logging in using the correct credentials again.

As you continue working with QBSE, you can as well open these articles as your reference:

• QuickBooks Self-Employed Overview
• Find articles, video tutorials, and more for QBSE

You can always add a comment below if you have any other questions. I'm here to continue helping and ensure you can open your account successfully. Have a good day!