Drum kit stems changing direction bet. flows

Hello, all.
I am working with a multi-flow score, and the stem directions/voice numbers of my drum kit are changing between flows (e.g. the kick drum is V2/stem down in flow 1, and suddenly V1/stem up in flow 2). Why is it doing that, and how can I make it consistent throughout?

Perhaps you have different options set on the Percussion page of Notation Options for each flow in your project?

Well, that was exactly it! But I didn’t set those differently; how do you think they got fiddled with?

It’s quite easy to make a change in Notation Options only for the current flow, so my guess is that’s what happened.