Is it a seat cover, or the plastic trim?
For seat covers, get some shirt stays; google them, it's more a military thing than anything; and run them under the seat. Make sure to get the ones that are straight, and DON'T go under your foot. Should come with 4 in a pack.
I took my seats out to do it. Ou have to run them right at the bottom of the cushion, or the electronics will be in the way. Just clip them to the front, bunch up the back, and make the shirt stays tight.
I've had mine on there for over a year, and only take them off when I wash the seat covers.