Bevelling sharp interior corners I am trying to model windows on a somewhat cylinder-shaped object and I cannot figure out how to satisfactorily bevel sharp interior corners of the areas around them.  A screenshot of what I am trying to do:



And when I try to just use the bevel tool:



I've also tried using the bevel weight modifier and selecting the edges I want to bevel, but it only seems to work up to those corners, even though they seem to bevel when the modifier is applied to the entire object:



So basically, how would I go about doing this? 

I'm a beginner so I apologize if there's something really important I've missed.  Thanks in advance!
If you are using a subdivision surface modifier, the easiest way to sharpen edges is with a loop cut and slide (Ctrl R)



This is where loop cut and slide is located


And if that doesn't work try adding creases to the specific edges