Firmware 01.07.00 Sound gain control  ther is none at all where is it not  on the  preference screen.

Hi. Thank you for sharing your insights with the new firmware v01.07.00 for the DJI Osmo Action and thank you for your valued support.

DJI Paladin Posted at 12-16 11:04
Hi. Thank you for sharing your insights with the new firmware v01.07.00 for the DJI Osmo Action and thank you for your valued support.

This seems rather understated bearing in mind what Mr Comics shows in the video - and I have confirmed.
If you have an external mic plugged in you can drop the gain when recorded by turning the 'sounds' setting to Low.
This feature has been requested in several threads, but it's there already like a hidden Easter Egg you have to find!
It would help if Firmware updates had proper release notes which told us all the things which have been changed.

An astonishing revelation, it doesn't seem to make any change if you don't have  a mic plugged in - but at least 2db lower gain on Low using external input.

rode wireless go adjustments

Imagine that.  I  did not even think of  trying that with the rode wireless go. I did say that its  not the bestest in the world either because  the Db is on the Rx and you have to be at teh camera to do that.  Lol

For DJI  when they are not in the Fatasy world of  c/p  maybe they will join the real world and answer.  They like any company have to follow tehir guidelines and say thnk you.  they are not allowed to  say anymret hen that.

gain control lead can be purchased to manually lower  the sound, this is not new. you can also Amplify any non-powered mic, that is also not new. a simple transistor, resistor and  3.0v  23C bat.   
Correcting Grammer

As the video I shown I r emoved had not a thing to do with any settings of the camera.    As DJI never put these controls in they Simply  raised up teh Db NOTHING MORE>

It wasn't your Rode mic, I see the reduced gain on Low in sounds with a Video Micro which has no way to adjust gain.

4wd Posted at 12-17 06:18
It wasn't your Rode mic, I see the reduced gain on Low in sounds with a Video Micro which has no way to adjust gain.

  incorrectly done.  the Wireless go I own and done with has the option on the Rx to adjust Db  high , med, low while   in operation. stay tuned for the corrected video.

4wd Posted at 12-16 11:25
This seems rather understated bearing in mind what Mr Comics shows in the video - and I have confirmed.
If you have an external mic plugged in you can drop the gain when recorded by turning the 'sounds' setting to Low.
This feature has been requested in several threads, but it's there already like a hidden Easter Egg you have to find!

Hi. Thank you for reaching out to DJI Forum and your insights with regards to the firmware. I will cascade this information to our designated DJI support team for further updated. Thank you.

here is the update