[image credit Gary]
There it is in the right foreground: a hot glue gun.
Use it to glue the pieces of the house together instead of trying--and failing--to set the sides, ends, and roof panels using the white icing that comes with the kit. You will use the icing only to stick on the little decorative candies, where structural strength is not an issue.
So instead of flailing around for a couple hours (only, probably, to have your house slowly sag apart as you helplessly watch), you'll be decorating it within 15 minutes.
You're not gonna eat it anyway, are you?