Try one of these articles:
- Add-on signing in Firefox for Android You'll see a warning in Firefox for Android when you try to install unverified or unsigned add-ons. Learn more about add-on signing.
- I can't play videos or audio on Firefox for Android 5.0 (Lollipop) If you're using Firefox on your Nexus 6 or Nexus 9, you might experience temporary issues with video and audio files. Learn how to fix them.
- Avoid and report Mozilla tech support scams Mozilla does not charge for software, upgrades or technical support. Find out about common scams and how to protect yourself from them.
- Firefox Health Report - understand your Android browser performance Firefox Health Report lets you know how well your browser is performing on Android and what steps you can take to improve it.