Extruder problems

I just purchased my printer last week, and so far I've really been enjoying it. Nevertheless, there have been some issues. The extruder has been clicking every time I print something- which I doubt is good for the motor- and the edge of the 3d printed piece surrounding the nozzle has been scraping against the print occasionally. Additionally, when I was attempting to change the nozzle size, part of that same piece broke! I've repaired it with some superglue, so hopefully it'll hold up. I've been using the 0.4 nozzle and standard settings.

My questions are- how do you change the hotend temperature to reduce clicking? And, is there a way to prevent scraping?

Thanks for any help that can be provided!

Changing the temperature: it's not very obvious, but you can create a new material in the Maintainence section:

Screen Shot 2017-12-13 at 1.10.03 PM.png

I made PLA.2 with 220 degrees instead of 210, and the extruder clicking is much reduced. Still can't print with the 0.2mm nozzle, however!