How often does the transmission fluid need to be flushed

Gm recommends to change the fluid and filter every 50,000 miles which is most cases is OK. Inspecting the fluid on the dipstick will tell a lot. If the fluid in a nice pink color that is good. If it is brown and burnt smelling it is time for service and a complete fluid exchange may be a good idea. If fluid looks good and service is performed every 50K no flush should be necessary. If you decide to have a complete fluid exchange performed, no flush chemicals should be used, they can do more harm than good.

rough shift foom first to second all others ok.can you please tell me what my problem is?