Global editing is sometimes critically important. You want to select a bunch of vias and change their size or you want to change a bunch of component orientation en masse. There's a million reasons this is necessary and the best way I've found to do this in Altium is using the little-known Inspector panel. Here's how it works:
1) Select the objects you want. If you get some extra things, that's ok. You can filter these after the fact (see the image).
2) Hit F11 to launch the Inspector Panel.
3) If you have some things you didn't want, filter them out at the top of the panel (again, see the image).
4) Change the property and hit Enter.
Watch as the magic happens.
Now if you want to be totally pro...you can use the lesser-almost-totally-unknown '!' key to substitute and existing value in an equation. So lets say you want to move all parts 100 mils to the right. If you find the X location field and type !+100 it will shift them 100 mils to the right. mm if you want to be all "worldly" about it.