Question My laptop lenovo legion y520 thinks my asus gn246hl is a television and i cant just make it 144hz i use newest hdmi

The HDMI port on the monitor only supports 1080p@60hz. The dual link dvi-d port is the only port on it that supports 1080p@144hz and you laptop doesn't have one of those. If you have the model with a displayport there are adapters(but they cost ~$100).
 
Displayport to dual link DVI adapter(going to cost ~$100 and most will only do 120Hz reliably), buy a new monitor that uses displayport. Again this is assuming you have the Y520 with a displayport. If you have a model without displayport then you'd need a monitor that supports those refresh rates through HDMI(not many of them).