Site Identity on Maxstore theme

Hello, I’m new to wp and am using Maxstore theme. My question is very basic and I have a problem changing the font size, color, margin size of Site title and Tagline of Site Identity.
I’ve tried editing the css using Editor from Appearance on the dashboard but it doesn’t seem to take any effect whenever I change anything on there ?? perhaps I’m doing something wrong.
I would appreciate it a lot if anyone could help me with this. I’ve been stuck on this for 2 days now. Thank you in advance!