If you have chosen the application to use "application font" then that means the font will vary with the default on the machine it is run on....If however you instead specify a specific font then it will not change size or design, on the other side you will need to ensure that that font is installed...
You do not need to change the font to a custom one everytime, just set the default in the font section of Options.
Check out the following articles:
http://digital.ni.com/public.nsf/websearch/dd59d28c6fe7ae9086256a34005ab731?OpenDocument
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/569a6d181945819e8625697b007272b6?OpenDocument