How do I back up my phone to iTunes?

I plugged in my iPhone (5s) to my laptop and all it wants is to save my photos to the photo app and I did that. But when I go to iTunes to backup my whole phone it doesn't show up. The little phone icon doesn't show up and when i go File>Devices-Everything in the devices tab is grey like my phone isn't plugged in (my name is also grey when I go to account). It may be that I don't know how to work the latest iTunes (which I have). I've tried plugging in my phone when iTunes is opened and closed, I've tried restarting my computer and trying to see if my iPad would work (and it doesn't). What am I doing wrong?

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How do I let others reply to my comments in Youtube?

Okay so on Youtube some people have it set so that others can reply to the comments they made to videos. Others tho have it so you can only like their comments. Currently people only seem to be able to like my comments but not reply to them. I want to change this so that anyone can reply to the comments I make on different videos but I have no idea how to change this. Also, if I am able to change it can I do it on my iPad or must it be a PC. If you aren't sure about this latter part it's okay.

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