my front & back screen window seals leak

there loose you can just lift them up, when driving fast the air lifts them from the roof/window

looks like person before me has tried bodging it and filling it full of silican seal but thats not worked, still poor inside the car (and it sets my alarm off)

how do the window seals actually seal?

im a best off buying some new ones or using some more silican?

how do you fit n seal new ones?

cheers lads