A house which I am attempting to copy is built in a U shape. The middle section which runs north-south has a pitched roof gabled at both ends. The wings of the U have flat roofs sloping north-south and vice versa with the highest edges nearest to each other. I am having a problem with the lower outer edges which stop short just before the supporting walls instead of having an overhang. If I attempt to move the edge, only the part furthest from the gable roof extends. It is as if the point where the roofs join is fixed even though extending the flat roof is not interfering with the gable roof. The gable roof was created as a normal roof insert whilst the flat roofs were created by picking points for inserted surfaces. Is there a way of extending the lower edges of the roofs?
Without a picture I'm doing a fair amount of imagining...but,
in general, you can either select the roof edge and drag it out past the exterior wall,
or check to see if the eave has an overhang like you want...make it longer if needed.
If still having trouble, best to show area of problem in a screen picture .jpg attached here....and post the .bld file for others to see and try to fix or explain to help you.