It took me embarrassingly long to figure this out. It appears that when you click the colour swatch on your nameplate to change your colour it pops up the pallet a fixed distance above your name. This means that clicking it when the nameplate is near the top of the screen has not noticeable effect as the colour palate appears off screen. Workaround: Drag the nameplate to the bottom, then click to chance colour. You can then right-click your name and select "reset" to put it back to automatic positioning. Tested on Firefox 77.0.1.