Hi

There is no way to do that at present, but it might be something that we look to do in a future update.

If you want to leave feedback for developers, you can use this link. Your feedback gets collected by a team of people who read it and gather data about the most common issues.

I hope that this helps.

Yes, selecting a background or a whole icon should be possible in a future update. It's already in Nightly.

Hello, this option should now be available to you in the Settings under Customise. You might need to update the Firefox app first.