Where you mount your 75 inch TV depends mainly on the set-up of your viewing room, including how far away from the TV you expect to be sitting. Expert advice indicates that your TV should be mounted at eye level when sitting not to cause neck strain, but it may be true that you tend to watch TV lying down or frequently host parties where the eye levels of guests will vary.
Use your judgment on what will be the best height for most of the time. You can read our guide on how to mount a TV for complete preparation before you get the screwdriver out.
In short, make sure you're not trying to mount your new, expensive best 75 inch TV with an ill-fitting bracket, measuring the dimensions and weight of your screen before looking for the perfect mount. Most will list the optimal TV size and maximum weight – pay attention to these, and you shouldn't go too far wrong.