Is it possible to update to the nightly build with hdr support and keep all my other addons and settings in kodi?
And if possible how do I instal this nightly build ?
And can I downgrade back to 9.2.6 if needed?
Or is it better to take a New sd card and fresh install with latest nightly build and reinstall my addons?
Can you make a New sd card with nightly builds with the usb-SB creator?
It's best to do a fresh install of the official LE 10 beta 1 release (or the latest nightly build) on a separate card and then update it with the test build (copy the tar file to the Update share via SMB or to the /storage/.update/ folder via scp and then reboot).
Upgrading from LE 9.2 is not supported (it might work, but depending on installed addons you can end up with a real mess) and downgrading isn't supported at all (you'll definitely end up with an unusable system).
The test builds I post here in this thread only contain a few additions that aren't in current nightly builds and if testing goes fine we'll include the changes in LE 10 / nightlies - switching from the test builds to LE10 nightlies or the next official release will work without issues.