When I set the unit of measure in the app to Imperial, does it change the RTH and max altitudes to Imperial or do they stay metric?
The app just shows metric on the RTH/Max settings screen.  
I live in a Class D airspace and have to get tower clearance to fly, which is no problem for me to get.  But, I have to make sure these settings are spot on because I have large trees around a lot of our parks.

Also, once I set these, do I have to reset them every flight?

Thanks

i would test it first in a open space .... to avoid an accident

100 meters are 328,08ft and 50 meters a 164.04 ft. The app is converting the imperial to metric by it self. The max RTH altitude is as imperial and metric too.

Before i forget. You can fly by the heighest tree and let the cam looks straight to the tree and fly upward to that  point as the tree tip is visible on the lower quarter of the screen of the mobile und you can look for the current altitude and you add 5 or 10 meters(15 - 30 ft)  to that altitude and set so the max RTH height.

When I set the unit of measure in the app to Imperial, does it change the RTH and max altitudes to Imperial or do they stay metric?
It's a DJI quirk that where you enter your RTH height is always in metres even if you have selected feet for displaying units.

Also, once I set these, do I have to reset them every flight?
Your Max altitude and RTH height will be the same each flight, but will probably revert to default values if you update firmware.

Thanks all.  I figured I should test it to be sure.  But, turns out that when your land is next to a mountain called "Iron Mountain", compasses don't want to work.  And, you can't calibrate the 3S compass standing on a giant iron deposit.  

Hi. Thank you for reaching out to DJI Forum. With regards to this query. As Labroides advised at post #4, When imputing the altitude it will always be in meters then the DJI Go application will convert the values to imperial if changed. The flight altitude settings will be saved, the only time you will need to set up this settings once again is when you deleted or the DJI Go. Thank you.

MacMacgyver Posted at 6-26 05:49
Thanks all.  I figured I should test it to be sure.  But, turns out that when your land is next to a mountain called "Iron Mountain", compasses don't want to work.  And, you can't calibrate the 3S compass standing on a giant iron deposit.

If ya stand there to calibrate the copass then you´ll get the magnetic southpole bellow you. If ya want to set the RTH height you´ll do it in metric units and the app convert that automaically to the imperial units. ya only need to think 1 meter are 3 feet and 2 inches.