I have a red line on one of the signals. I do not know what it is. Help

Try re linking your RC to your Quad.  

rreindl Posted at 2016-8-6 01:58
Try re linking your RC to your Quad.

I will try this. It flys but drifts and has the red line

firefighter5138 Posted at 2016-8-6 02:00
I will try this. It flys but drifts and has the red line

Also are you flying in "P-Mode", p-mode position on the remote?

Looks like you Obstacle Avoidance System has been turned off due to low battery.  Try putting in a fully Charged battery.

If the above suggestions do not work please let us know which quad you have. I have the P3A and had the same as you on the screen shot and the re-linking worked.

The red line means obstacle avoidance is not on, it doesn't work at night.
The full manual is in the app, from the home page the top right icon (graduation hat) will take you to the manual, tutorial videos, and flight simulator.
Please take some time and read the manual and watch the videos.