Funky font when printing PDF

Hello. 
This is my 1st time posting to this forum. I tried to find an answer before posting, but I couldn't find one (that doesn't mean one doesn't exist.)
I have a blueprint that was sent to me as a PDF. It is a LONG print and it should be printed out on a plotter, but we don't have a working plotter in-house. Anyway, my boss was able to use the POSTER print method to print it out on (4) or (5) 11x17 pages in portrait mode. The problem is that when it's enlarged like that so that it can be read, SOME of the dimensions and letters are changed to something unreadable (numbers and letters w/ diagonal lines added to them). The 5 page printout is bigger than that on the 4 pages, and has more unreadable dimensions / words than the 4 page one. (The original print has NONE of the funky font.) What's also weird is that, for example, the 5.4 dimension is listed 3x in one view and 1 is funky but the other 2 are perfectly fine.  I thought that I had found a fix online, but I think it references an older version of Adobe? - at least that's what the IT guy said. (There is NO Adobe printer, nor Adobe PDF Settings tab.)  I'm using Windows 10, and Adobe 10.0(?). 
I've attached 3 pics to show what I'm talking about.
Thank you in advance for any help or fixes you can give me.
~Rusty