Two things....

One... You need to invest in a good wire crate. A flimsy one can actually be dangerous for this dog since she seems to be very strong. The key to crate training is to get the dog comfortable in it and not make it a major threat when she is in it. Start by putting all her treats and dinner in there while you are at home. Put her favorite woobies in there so she has to go in to get them. Put a nice (but throw away) blanket in there for her. If she destroys it, no big deal. Put a blanket over 3/4 of the crate to make it more like a den. All she can see is out the front. Go as far as getting into the crate with her and giving her comforting pets and soothing talk. Your goal is to make the dog love going into the crate. Everything good happens when she is in the crate! Do not put her in the crate and just leave her there without introducing her to it properly first. She will definitely learn to despise it.

Two...remember you are dealing with a one year old dog. Basically this is a tweener or teenager in training. Eating your furniture is probably a sign that she is teething more than vendictive behavior because you are not home. Dogs do not have a sense of time so one hour or four is the same to them.

Do you have lots of chewies around for her to occupy her time while you are away? Hard natural bones that take days to chew, stuffed kongs, buster cubes (kibble inside a cube the dog has to work to get out) or a bucket of ice cubes work best. If the dog doesn't have something good to chew on, it will find something and it will be your furniture! If it is teething, this could last until the dog is around two years old since it is a larger breed dog.

You didn't say if you are doing any obedience work with your GSD. I would strongly encourage this so you can bond with the dog and the dog will learn to respect and listen to you as the alpha over it. Take some positive steps in helping the dog resolve this issue. She will respond!

Good Luck!