The horizontal scroll arrows are not working on Amazon prime video using Firefox on a pc running Win10. It hasn't worked for some time and I thought it was an Amazon problem, but I've tried other browsers and devises and it works on all of them EXCEPT Firefox. My Firefox for pc is up to date. I have uninstalled and reinstalled twice. I have tried cntrl +/- thinking maybe I just wasn't seeing them - they're not there. All drivers are up to date. I don't want to use another browser but i use Amazon prime video a LOT and this problem makes it nearly useless. HELP please?