To correct the previous formatting that specified the Appendix titles should be on separate lines, you can either download the most recent version of the pittetd.cls file found in the LaTeX template(https://etd.pitt.edu/latex-template) or edit the file currently found in your template.

Find the line that is normally line 748 and change it to read: 

{\normalfont\bfseries\centering
        Appendix\thechapter\space\expandafter{#2}\par}  

If you have any questions, please contact ETD Support. (https://etd.pitt.edu/help)