I've spent hours trying to solve this radio button form issue and read thru a dozen posts. I have a SP list with a Power App form for data entry and edits. I have a radio button field called Needs Funding? that defaults to No. That part works. However, when a user updates it to, say 'Yes', saves, and then opens it in edit mode, the record reverts back to 'No.' For the radio list, I have 3 options that pull from the List Settings on the SP list: Yes, No, TBD that pull through the Items field. That works fine.
In the Default field, I've tried just a simple "No" and the snippet below. They all set the default to No and allow and update, but when the items is opened again to edit, it reverts back to No. The user has to manually reset it to the non-default value each time it's opened. How do I resolve this? Thanks!!

If(FormMode.New, "No", ThisItem.'Needs Funding?'.Value)