Do I need to caulk behind doors and windows? Vinyl siding isn't flush

I've looked a decent amount online and have gotten mixed reviews.

Do I need to caulk behind the windows and doors of my house? The top and sides of the windows aren't totally flush to the vinyl siding. Should I caulk behind and on top to prevent water?

The house was built in 1996 and we just moved in. Trying to take care of small issues.

I've attached pictures.

Thsnks

It's a picture of a the top of a sliding glass door and a window.

 

You absolutely DO NOT caulk inside the integral j-channel where the vinyl siding meets the window.

Hopefully there is housewrap behind the vinyl siding. If there isn't, you have big problems and should consider removing siding under windows to see how much damage has already been done.

 

In those first four pictures it's hard to know what where even looking at with them being to close up and sideways.
That first picture has me totally confused.
Looks like 2 X lumber sticking out from the wall for some strange reason, No Z molding.
Second picture looks like someone blobbed on caulking at the top of a trim ring where if the siding was installed correctly it never would have been needed.
Third picture looks like someone needlessly blobbed silicone caulking inside the J molding, now how's the siding going to be able to expand and contract?
Forth picture, I have no idea what it is your trying to show because it's to close.
A few rules of thumb for properly installed vinyl siding.
The wall has to be covered with house wrap, windows and doors flashed.
That water poofs and wind proofs the outside walls.
Siding has to be allowed to expand and contract or it's going to buckle.
Done right there's no need to caulk anything.