Look through your manuals for the trailer and see what the paperwork for the brakes say. On my new trailer, they claim to be "self adjusting" and never need to be touched manually. My last ones had an adjuster wheel. Without looking, I think Dexter makes my new ones. There still should be an adjuster in there somewhere, you just might not need to mess with it. On another note, I haven't looked to see on this trailer, but the adjuster on the last one was really hard to see..had to almost do it by feel.
2012 Chevy Tahoe LTZ - HD tow package
2017 Rockwood 2703WS Emerald Edition