If you want to use other input for screen switch or to enter in setup screen, you need Accessory set in Config > Input.
The toggle "channel" set on config tool is not the channel from Rc receiver but the order in Rcinput tab :
0 : Throttle
1,2,3 : Roll/pitch/Yaw
5 : Flight mode
6 - 8 : Accessory0 to Accessory2
So if you want to use the "channel6", first setup the accessory0 in Rcinput tab.
I have fixed the issue when osd go to setup screen while RC TX is down yesterday
This issue can cause some calibration changes not needed... Check attached hex.