When watching a video, if you set it to 720p, sometimes the video resolution is automatically reduced to 480p or 360p. Occasionally, it seemed to me that the resolution, on the contrary, increased to 1080p. I tried turning hardware acceleration on and off, it had no effect. This does not happen in other browsers.
The right place to ask is the Godzilla's support forum.
“All these years that I had spent in the service of mankind brought me nothing but insults and humiliation.”
― Nikola Tesla ―
“I'm such an open book, but you shall read between the lines.”
― Neo Buddha ―
Firefox Portable is a separate product and is not an official Mozilla product. So official support would be right if it redirects the question to the Firefox Portable developer.
The copy of Firefox within Firefox Portable is unaltered.
Sometimes, the impossible can become possible, if you're awesome!
If Firefox is what you are using try posting and enquiry to https://forums.mozillazine.org/index.php
Likely they will be able to help.
Use Portable Apps on both Flash Drive and HDD/SSD.