Font is not registering and changes to random symbols

++ adding on to the expert's suggestion.

About Font embedding and substitution, please go through this helpful article here: https://helpx.adobe.com/acrobat/using/pdf-fonts.html 

Also, some related discussion might help you finding the root cause of the problem: https://community.adobe.com/t5/acrobat-discussions/text-changes-to-special-symbols-with-saving-pdf-in-acrobat/td-p/10634321 

Thanks,

Akanchha

Is it just Acrobat that is showing it incorrectly? i.e. have you tried opening it in a browser?

Two possibilities:
1. They did not properly embed/subset the font so your System is trying to replace it, unsuccessfully.

2. Even if they did, your Acrobat may be configured to use local fonts, and it is unsuccessfully doing so. Check your Acrobat > Preferences > Page Display: uncheck "Use local fonts" if it is, then try again.