If I already have xenforo installed on a hosted server, and had imagemagick installed after, it should still work right?
Cause I cannot click the radio button for it and they installed that for me.
With ImageMagick pecl extension installed-enabled you should be able to see the .gif images in your forum.
I don't know what radio button are you looking for?
And in addition to being installed, normally the PHP processor needs to be restarted (in the use of Apache by restarting it, in nginx by restarting the php-fpm process).