This concern was brought up on Main Meta:
Please make the stickiness persistent, at least from main to meta if not network-wide
I know that a network-wide flip for the stickiness is an, uh, sticky point, but I was pretty surprised to find the top-bar to stick to the top of the screen on meta.SO after I'd disabled that feature on SO itself. Add additional switches for meta if you want, but I think it's reasonable to assume that if a user has set the top bar as fixed on a given SE site, they also want it to stay put on the corresponding meta.
And is under review by the SE Team.
Stickiness global preference
Concern: SO top bar is sticky by default with a preference to unstick it. Network site top bar is not sticky by default and there is no way to make it so. Can we get a global preference for setting stickiness across all sites?
Explanation: We think this is a good thing to have, now we just need to figure out how to make it so. This could be a somewhat expensive setting since we currently don't have any global settings. That said, we are actively investigating it.
I think we just to have wait until this is reviewed network wide.