Array modifier questions from a beginner I am following a tutorial at https://www.youtube.com/watch?v=emT-CL957HE
Around 19:30, how does he turn off the array modifier for the duplicate? No matter what I do, they seem to share the same behaviour ie shadow the parent - can't figure out how he did it in the video.

Some other questions:

-What is the significance of Ctrl-L (at 18.30 and 20:00) and when is it used? I can't find any good info on the net that can provide a good example of the usage especially in the above context.
-What is the purpose of clicking Apply? Is there something that is irreversible once Apply is clicked?
Thanks in advance.
19:30 He basically duplicate the set of windows with CtrlD and then proceeded to deleting the array modifier that was copied during the duplicate fuction.

18:30 Ctrl L - It's basically a quick method to select a mesh and all it's joined elements. This is extremely useful if you have multiple sub-meshes joined together to form the main object. Sometimes you may want to select that one sub-mesh to apply a material or hide it temporarily.

Applying a modifier makes it permanent and irreversible. However you can undo it if it's still within the undo range. Usually you will want to apply modifier at the end of the modeling process.



Extra Note

Personally, I usually just hit L, this works in UV editor mode too when you want to select a UV island.