At the bottom “find results” type right trigger, then at the end of this line hit the googles icon so it will search in every blueprint. Or Right clic on your gamepad right trigger and “find references” and
tick the googles.
you didn’t tell me if your controller is correctly set up. If you are using another controller than the one created with the project (third person controller or topdown controller) you have to set it in the project settings. (edit / project settings / map and modes). On this screenshot mine is “main controller”. If you don’t have any keys working then this should help.

