Passat roof rail black plastic strip gutter thingys?!

[dodge]

On the estate there are gutters which run just to the side of the roof rail itself. Inserted in here is a long strip of painted plastic. I noticed both these strips have somehow shifted back a little so they are almost touching where the gap in the boot it and at the front they need shifting forward a little.

I started to lift the strip out from the front but felt like it could break quite easy so i'd check on here 1st if theres any technique to removing them and reinserting?

(since picking the front bit out it now keeps popping up after i've driven somewhere Grrrrr )

also what is the purpose of this gutter and plastic insert LOL