Acer Predator Laptop, the 1660ti one i dunno the name- have external monitor

How do i make it where the game only shows up on the external monitor, liek a dual monitor setup, instead of the game mirroring on my laptop screen, it feels like it causes a delay and I play Rust which is a fast paced game open world fps where I rage when i die with loot.

any help appreciated, i am using extrenal mouse keyboard and monitor.

also while i'm asking, this laptop appears to not have a hard wire ethernet connection, which really sucks i didn't know that hwen i bough *****