Type about:preferences#advanced<enter> in the address bar. Under Advanced, Select Update.

[v56+]; Type about:preferences#general<enter> in the address bar. Select Update.

Check "Do Not Check For Updates."

Also turn off Use a background service to install updates <Windows Only>

I forgot to add, the way data is stored was changed, so if you want your current data, you will need to use sync.

VadimTver said

Hello! I want to install Mozila Firefox version 52. How can I disable all updates? The browser is constantly updated!

Hello VadimTver,

Surely you don't mean to downgrade  ?

If you really need that old version, you could download the portable Firefox 52 version, which doesn't interfere with the current release version and your profile :

https://portableapps.com/apps/internet/firefox-portable-legacy-52

Would that work for you  ?