[NocturnalWaffle]

If you press F2 you can change the setup for the top meters and switch it out with CPU average or other combinations of cores.

[Piskvorrr]

...or if you're not the interactive type (or deploy untold millions of images), edit .htoprc .

Hm. Given the opacity of that config file, I went the way "configure interactively, then roll out the new .htoprc"