What would cause my shift indicator light stay on. I have changed everything

Hello, The alternator and battery will not affect this light directly. However, indirect effects of changing the battery and alternator may be playing a role here. When the batter and alternator were changed, if there was any sparks, arching, grounding the positive post, removal of the alternator before disconnecting the battery, a wrench on the positive side or alternator bumping anything metal, or a plethora of other scenarios resulting in grounding the positive battery terminal, systems on the vehicle will start acting strange, and require repair. In this case, the vehicle will need to be scanned professionally. This will indicate to a technician why the transmission controller 'thinks' it needs to shift. This failure could be electronic or mechanical, but either way, scanning will be required to understand what is happening there.