My 144hz Monitor (Samsung C24FG7x) runs in 60hz (I use display port)

Did you try a different cable? Did you get a cable with limited lifetime guarantee at a local store? Did you run the "factory reset" built-in to the TV/Monitor? You should unplug both units and restarted (turn on monitor first then PC). Also when you post you should say what video card you have. 1/2 the Hz issue is the monitor, the other 1/2 is the video card or it's software control panel. They both equally can prevent full refresh rate.