Header problems

Hello I am having trouble customizing the header logo with the theme I am using. The “New Yorker” theme does not have a header section to easily change the font, size, etc of my logo. I tried doing it on my own and noticed that the font that I want appears for about 4 seconds when the page is loading and then goes back to the default theme font. Could someone let me know how I can fix this so I could use the logo I want? The website is http://www.elpaisanoonline.com thank you