Check that Bluetooth is on for all phones and that FOCUS is allowed to use Bluetooth (Settings → FOCUS on iPhone). Keep the phones close together and check that the code is entered correctly. If it still does not work, close the app on all phones and start again.

See For observers. In short: Settings → Google Sheets, create a sheet or connect to one shared with you.

While the app is being reviewed by Google, invited test users see this warning. It disappears once the review is complete.

Use the Send by email button in the export sheet – the file is then always attached. The Share option goes through the phone's share menu, where not all email apps include attachments.

In Observations: tap Export data, mark the observations and tap Export. Then choose CSV file or – if the app is connected to a spreadsheet – Google Sheets.

No. FOCUS only writes in its own tabs (Instructions, Data and Codebook). If the sheet already has other content, you see which tabs exist and confirm before the app connects. If the sheet has its own tab with the same name as one of FOCUS's tabs, the app does not connect at all.

In Observations: tap Select, mark the observations to remove and tap Delete – or swipe a single observation to the left. You always confirm first. Uninstalling the app removes all observations from the phone. Rows in a shared spreadsheet are deleted in the spreadsheet.

In the app: Settings → Google Sheets → Disconnect and Sign out of Google. Access can also be revoked at myaccount.google.com/permissions.