Hi habib,
So for wyze cameras, both “SD” and “HD” are 1080P resolution. “SD” just have lower bitrate to save both your bandwidth and SD card space. If you choose live stream to be “HD” or “360P”, then you will get 1080P recording with higher bitrate in your SD card (about 5.5MB/minute). And if you choose live stream to be “SD”, then you will get 1080P recording with lower bitrate in your SD card (about 3MB/minute). We don’t record 360P to SD card, only 1080P.
As for multiple devices viewing with different settings. It only depends on which one you change last. For example, Both phones are watching same camera with “HD” and then you change one to “SD”. Then your recording will change to “SD”. Since that is the last change you made. Again, here the “SD” still means 1080P resolution just with lower bitrate.