Best practice will tell you to NEVER change core WP files (and I'm not asking you to here.)
Best practice will tell you to NOT change core Theme files, but to setup a Child Theme (eg customizr-child) in order to change Theme behaviour. This usually means styling changes in style.css
This also helps when the Theme is updated as core Theme files will be overwritten and you will lose your changes.
This fix means changing a 'class' file, and I don't see a way of doing this within the child theme. If there is, I'm sure someone will correct me.
So here goes.
1) Look in wp-content/themes/customizr/parts for a file named class-header-menu.php
2) Take a copy of it and store it away safely. If my fix doesn't work, you can either restore this file back in the parts directory, or else Delete the Theme and Add New the theme again which will overwrite everything in themes/customizr
3) You need to edit the file left in /parts, and replace all the code with the code at this link:
http://pastebin.com/TLdHsx91
4) Reload your site, and the Paypal button should appear in the bottom-right of the navbar under the Tagline.
5) Take a further copy of this edited file and store it safely. The next time Customizr is updated (eg 3.0.5), you will lose this change. You will need to resurrect this saved file in /parts after the update.
6) Test and confirm it works as expected. If not, see 2).
IMPORTANT: This code works for burtonsvillepanthers.org only