Set your resolution to 1920x1080, that has nothing to do with changing the Video Card settings to 144hz.
Goto Start ->Control Pannel (Settings in WIN10) ->Display -> Advanced DIsplay Settings -> Display Adapter Properties -> Monitor Tab (middle) ->Screen Refresh Rate is a drop down. Select the refresh rate of your choice. Click Apply and OK.
Youll be set.
You can only do one Refresh Rate at a time. (cant do 60hz and 144hz with 1080p at the same time)
If you have 2 monitors, your ASUS 24" will be at 144hz, the secondary will cap at 60hz, no issues.