As long as your client has not shared your report with the company that asked for it, they can change their answers at any point - any bank accounts connected and income tagged will be saved so they won't need to redo them.
It's important to note that a report cannot be amended once it has been shared.
If the question was in the fact find before they connected their banks, then go to the bank's screen and hit "Back to Questionnaire" - then hit the pencil icon next to the answer you want to change. This will take them back to that point in the questionnaire and you can continue back through from that point.
Note that once they amend an answer they will need to continue through all the remaining questions to the end of the questionnaire - this is to allow the amounts that are calculated by the fact find to be recalculated based on their new answers. Changing answers may therefore change the amount they need to demonstrate in your accounts.
If they need to change an answer in the Source of Funds survey then they can hit the dropdown next to the "Amount Proved So Far" and edit or delete the response in question:
Must note, if the client's circumstances have changed and they need to produce a different report then a new request must be sent to the client.