In control app click on parameters at bottom and there you have your A and B, by each one there’s 3 dots by the name, you can click that and a drop down menu appears and you can choose to load .h9z files or .tide files in either A or B slots.
Also no one has shared anything yet but we’re hoping this will be the official place to share h90 stuff
https://patchstorage.com/platform/eventide-h90/