General rule of thumb - set everything to max with 21:9 ratio. I have not yet seen a FW version where it would be advisable to set anything to lower than max.
V2.10T was test FW VIOFO offered that was supposed to brighten the image under direct sunlight, it was quite dark after V2.5. Now this version is not available from that link anymore it seems and there is V2.9 instead, that is supposed to remove the automatic locking of parking files.
