I was able to achieve what you wanted. If only the third word needs to be changed, just include the Source Text for the bold font that you wish to use in the Motion Graphics template. Do not add Source Text for the other two lines since they don't change anyway.
Make sure to use the Character panel in After Effects to center align text before exporting the template, that way all text stays centered.
Hope this helps.
WONDERFUL, thank you. I'm going to try it now.
It was one line, so I did break the one line into two, one text layer with the Regular text and one text layer with the Bold Text. I justified it left and right It is working and the work around is that the user will have to put in spaces to make the text centered. Thank you. The idea of breaking the text into two lines what what I needed.!