Is there a way to show more PDFs without having to scroll left or right?

Right now the max PDFs that I can have opened without having to scroll left or right on the top PDF tab bar is 9 PDFs. I would love and really need to have 12 PDFs opened without having to scroll. Is there a way to "zoom out" to make the PDF tabs smaller to fit more? 

I've seen others that I work with who can fit several more than me. Please help and any information will be helpful, thank you in advance!

Gilberto Garcia