Did you say you have a new Ford? Then you need to hook the trailer up to it and scroll down through the truck settings, find the trailer breaking part. Re-set to the heavy trailer setting.
I was under-impressed with the breaking on mine (2016 F250). While sitting in a parking lot on our last trip, waiting for the DW shopping I found the setting. I move it to heaviest trailer setting and left the gain at 10. Once back on the road we came to the first light (25-30 mph) I stepped on the brakes with the usual force... Thank gaud for seatbelts or I would have done a faceplant into windshield. The smoke from the wheels rolled down past us while we waited for the light. The wife asked, "What the hell happen"? "Did someone just hit us?" I said,"No, I think the brake adjustment must have got move, I'll readjust it."
I never could find this adjustment on the dash when the there was no trailer connected. It all makes since now, it's adjusted differently for each trailer you have logged into the truck's computer. To bad they didn't say this in the owner's manual. The gain is now at 7.
BTW: On the light trailer setting, sliding the brake control lever over never would lock them up. It sure does now!