I'd suggest posting some photos so we can see what you have and what can be done.
The gas struts can sometimes be installed incorrectly at the factory. That happened to a friend's TT and they weren't even close to being right and they needed to hold the lid up. I redid them for them and it opened easily afterwards. I have seen a diagram on the 'net somewhere before that shows the correct mounting positions of the brackets and the correct strut rating for the lid + mattress.
The attachment points of the gas struts sometimes need improvement by adding reinforcement, sometimes they use any old screws that are close at hand and sometimes wood can be split. You may need to add some wood backing or maybe a piece of plywood to increase the surface area the brackets are attached to.
I also modified the under bed storage. I added two drawers and a fixed tray above them and a removable tray on the other side. This increases the utilization of the space inside the box quite a bit. Things are so much easier to find and get to than plastic bins and cardboard boxes. Note that I installed 2x3 blocks for the brackets at one end. This makes the lid stay closed better because the strut exerts a slight downwards force when the lid is closed.
I also removed the OSB that the lid originally had and replaced it with plywood. The lid had quite a sag in it. Hard to see in the left photo but I installed a small strip around the perimeter on 3 sides and rounded off the edges with a router so that the edge is nice and smooth to grab onto and the sheets won't catch on it either.