Arranging my games to Collections

[syncx86]

I'd like to arrange my games to Collections in the Steam Client, is there any way to select multiple games at once, or do I have to do this one by one?

Additionally, is this info stored in the cloud? So if I reinstall windows, etc, will my game collections be saved?

[Dan5000]

Hold ctrl and click on all the games you want to do an action to.

Alternatively,
if you have a whole list of games underneath each other, click on the first game and hold shift, then click on the last game in your list to select every game at once.

Yes your collections are saved.

[Matti2706]

Wanted to ask that if I delete install of any game, will those saved game files be stored somewhere?