For a long time I struggled to select objects, but I just can't GRAB THEM. Either they just won't get selected or I get another object that I don't want. So I understand why you turned to 3D, it's easier to make a selection that way. But there's a problem in 3D... it's hard to move objects accurately on the x-y plane.
Before you go into 3D, try to play with the 2D window. There are different ways to select an object. There's the quick selection
, which is convenient when selecting large area objects. But for a group small objects, you might want to draw a selection area ( it can be any shape, usually rectangle ).
Now, as for objects that's hard to grab, move your cursor around the objects, especially the corners, because that's where the 2D hotspots are located. Think of 2D hotspots as spots on the objects which you can grab with you hands.
Finally, if all fails, like you did, switch to 3D, select the object, and move it to the ArchiCAD Layer ( or any layer that contains no objects, the ArchiCAD layer is usually empty for the 2D window), then, using the Quick Layers, hide all layers, except for the one the object is on. This way the object you want to select will be the only object visible on the 2D window, select it, and make other layers visible again.
Unfortunately this seems to be the only way to select an object in 3D and then select it in 2D.