What version of Mint? https://blog.linuxmint.com/?p=4244 see screenshots That's why I run my distro and Mozilla version (from the download folder). Distro updates their version and Mozilla handles theirs. Try downloading Firefox from Mozilla, run firefox-bin from the folder. https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

I use sync so all browsers have my data.

..I can'T UPDATE THE LATEST FIEREFOX VERSION, I don't know what happened, but I need help

Is this with the Firefox package builds from Mint or is this with the Firefox Linux tarball from Mozilla?

If it is a package build of Firefox from Mint and there are no more updates in the package manager then your version of Mint is likely old and no longer supported in package updates.