I am new here on this 'forum'. I started learning blender about a year ago, and this day I am still a bit learning. For 3D Modeling for a game I need to use triangle faces in stead of square faces to make sure that the faces are visible in game. What I do is just make a face to delete the normal faces in the model and delete them with the X and then 'only faces', and then select 3 points and press F. But to do this for the whole model that will take a very long time. Is there a easier way to do this?
Select everything in edit mode with A and press CtrlT
Alternatively, if feel that you might still need to make changes while it has square faces, you can add a Triangulate modifier to the model. This will triangulate the faces, but you can still edit it as if it had square faces. This modifier can be applied or removed any time you like.