Sorry if this is in the wrong spot, but i'm still getting acquainted with this site.

So in servers i have seen, portals (stargate) only go to a certain portal.

So portal A only goes to portal B (vise versa),
and portal C only goes to portal D (vise versa),

but when i create a portal, it allows you to choose the way you want to go with the sign.
How can i change this?