Kitchen cabinet door doesn't stay open
How can I have it stay open until I want to close it?


Generally, the solution to this is to adjust the hinges. 

For example, European style cabinet hinges have adjustment screws which allow you to make small adjustments to the position of the hinges. 


(adjustment screw indicated with blue arrow. The clamping screw AKA locking screw is the one to the right of it)

If a cabinet door has hinges on the left hand side and tends to swing shut, you can position the bottom hinge further towards the back of the cabinet. Loosen the clamping screw and push the bottom of the door inward a tiny amount. It may turn out to be easier to do the opposite at the top.

As well as adjusting in and out, you can also make small adjustments left and right. This is usually for setting the gap between doors for the right appearance but it can also affect the way the doors close. If necessary I would try to adjust the bottom hinge to position it further to the right (rotate adjustment screw clockwise) and maybe adjust the top hinge to the left. You need to loosen the adjacent clamping screw (silver in pic) before turning the adjustment screw.

I would make small adjustments until the cabinet door behaves as desired.

Hinge details vary, check online (including Youtube videos) for guides for adjusting your specific hinges.

In the worst case you could add a friction-stay (sliding stay) to the top of the door but that really shouldn't be necessary.