Many of us have complained over that fact that we cannot simply disable auto-sort by setting a FileMaker property to disable it after an initial sort of the records.
There is a trick I learned here from ULearnIT that can serve as a work around with a bit of careful design work.
If you perform a script that stops with an indefinite pause, you can edit the records, but they will not resort as long as the script remains paused. Thus you can kick off a script that sorts your records and then it pauses to disable the auto-sort. Buttons on this layout will need to terminate this paused script by using Halt Script as a final script step or the halt or resume options in button setup.