The top has tabs that fit in a slot, the bottom has tabs with a hole for a screw. If your seats are aftermarket, check the bottom edge, they are probably bent upward, just bend down and fasten
The aftermarket rumble backrest springs have the tabs like the originals at the top ,but, the tabs are made out of much thinner material and bend easily when you close the lid. When you open it the springs fall out. I replaced the tabs with thicker metal and all is fine now.