FileVault problems

Hi,

I'm trying to switch on my FileVault on my iMac but it is not happening. My understanding is that is better to have it on for security, right?

All that I'm getting is when I try to switch the FileVault on it's asking me for the password for the computer, so I put it in but then nothing happens. I'm pressing FV but it doesn't come on. Can I use my computer without it?

And if better not, how to fix it? I looked up some videos on YT about creating additional admin or login to the recovery systems and looking for a fix but it didn't do anything.

Please help.

Many thanks!