You need to invest some time in what groups and components are for, how to name them and how to use layers.
Groups are on their own, like all the studs that you have now. Change one does not affect the others.
The rafters aren’t even grouped as component, nor as individual groups. Their geometry is not separated as single component instances.
Make one rafter (length doesn’t matter yet) > Make it a component > copy that component to get one roof side filled > enter one of the rafter components and change its length. All the others will change the same way.
p.s. groups and components are to separate their geometry from other geometry.
Components have the advantage of "change one instance > change all same instances"
All basic geometry should stay “on” Layer0. Groups and components may have some other layer assigned to them.
And with layers on/off you controle their visibility.