Common options to mount the flight controller to the frame:
- double-sided tape
- stand-offs and/or screws
- rubber bands
Elastic mounting material helps to isolate the flight controller from motor vibrations and can improve performance. A DreamCatcher frame is a good example for effective FC vibration dampening.
The position of the flight controller on the frame doesnt matter. You can move it up/down, left/right, forward/back.
What is important: attitude and orientation. The FC should sit perfectly level and point straight ahead.