You should experiment, but I've found that I can greatly affect the temperature variation by moving the position of the first flame diffusor, the squarish steel thingy on legs.
I move it to the far right because my monkey brain thinks that will move more of the heat to the left (to even it out some) but one time I assembled it and pushed it to the left...and it seemed to make the left side hotter. I need to devote some time to experiement, but I've got kids and just haven't had the drive to play with it
also like Bruno said, I like that I have a cooler side and a warmer side honestly. The last time I checked the temp variation was about 20-30 degrees once it had reached the desired temp