Hi,
first of all, you need to think about using it for only one website or multiple (all) hosted site on this special server.
You can have a look at /etc/apache2/sites-enabled -> here you can edit the domain settings - this changes are to be overwritten on any changes for that domain in i-mscp!
Or you can add that (I prefer using this option) in some kind of hidden folder (I am joking)
or, if you want it for ALL (future and changed) Domains
you may want to change
to look like this:
Regards
Joe