I previously had a MetaMask extension on FireFox and it would open as usual. Several days ago, I opened Firefox and the MetaMask icon in the upper bar wasn't there. I tried to download it on the browser several times and eventually got the download and entered the seed phrase and, with some outside help, established the extension again and recovered my tokens. So all was good. But today I opened my FireFox and the MetaMask was missing again. Can you please help me find out why it is missing and how to keep that from happening again. Thank you