I just gave a example.You should read what is binding loop.It clearly says you have a binding loop.
settings.extendExportFile is bound to textfieldId.text
textfieldId.text is bound to settings.extendExportFile
Whenever settings.extendExportFile changes which trigger a signal to change textfieldId.text and in turn this trigger a signal to change settings.extendExportFile.This will be happening in a loop, which is known as binding loop.