Square bolts?

[Briansol]

What are these called?

A couple of my window latches are lose and I don't have a square drive tool

 

[TurboMirage]

Square head screws.. your cheapo depot toolkit should have them. My old cheap ones did. Even the newer better husky set did. They were always in the bracket row with the other hex driver tools.

 

[E_SolSi]

Square recess bits / Robertson bits

I've mostly seen them used for decking

Should be able to get a set anywhere that sells bits, if you don't already have them in one of the multi bit sets that come with every tool / drill kit on the planet

 

[Jeef]

Sq2 most likely.

 

[BigJ]

 

[reckedracing]

There is a chance they are loose, because they need to be.

Depending on the fit and finish of your windows, and the cost vs benefit calculations of the builder, sometimes those window locks are a bit wonky.