When your create a new file on Photoshop CC, what's the resolution you use? Not sure what number I should but in there.

Thank you !

Completely depends on what you’re working with and intend to do mate.
For example when I create signatures I go by 1600px W/ 600px H which scaled down will be 400/150 (jsp pix size limit).

What are you aiming to create? Maybe I can help.

I usually do my sign directly from 400/150, do you suggest that I should scale it down afterward ? Also I have an option on Photoshop CC that after I set the resolution I want, I have the option to put the resolution per pixel (i think), what number should I put in?

Thank you !