Crack appearing in the window sill!

Hi everyone! I have recently bought an apartment that's kind of a fixer upper, and I've pretty much changed out everything in one of the bedrooms with the exception of the window and window sill. However, I did change the window trim, and I recently discovered that since then, there is starting to form a crack in the window sill!

It looks fairly cosmetic, though being an amateur, I don't have the expertize in being able to decide whether or not this is fairly easy fix that I can solve by applying a little bit of wood filler, sanding down and painting, or if this something that requires more work.

Any help, tips and advice will be greatly appreciated! Pictures attached.

 

Whoever did the trim used plywood, and put a 1/4" solid wood edge on the cut edges of the plywood. And either didn't glue it or didn't use enough glue when he put them together.

So that's the crack you are seeing. There's no perfect way to seal that. You might try to grab a bottle of Titebond white molding & trim glue. Squeeze it down into the joint and wipe off the excess with a wet cloth. Then once it's dry, you could fill any voids that are still left in that crack with spackle and give it a light sanding with 220 grit. Then a fresh coat of paint.

 

Thanks for your reply, XSleeper. Would those be the joints by the corners of the sill, or between the actual window frame and the sill? The crack seems to be along the actual sill, roughly 0.2 inches from the window frame.

 

I'm talking about the crack (in your question) that your black arrow is pointing at. Where he added a 1/4" thick strip of solid wood to the plywood that he ripped and used as a sill.

 

I might have placed the arrow little bit too high up, sorry for the confusion! The crack is little bit below, in the red marked box in the picture:

 

I don't quite understand why you don't think I know what crack you're talking about.

 

My apologies! English is not my first language, and I'm pretty much an amateur.