Can I set priority for QoS on RAX48 router?

I see where to set low, medium, high, or highest, but when I hit save they do not save.

My desktop wired computer should be highest as well as my cell phone. Everyone else's devices can be on normal.

My Samsung S20 Ultra is having issues using 5G. I originally did a speed test and it was very fast, but then it started not working or intermittent. Putting it on 2.4G works fine.