Can I change the results to show number of respondents instead of %?

Yes, within the PowerPoint Add-In you can select four different data label types.

From the Display Options menu select the data label type drop down menu.

The four different choices are;

% - Shows the number of votes as a percentage

123 - Shows the actual number of votes

% (123) - Shows the number of votes as a percentage followed by the actual number of votes

123 (%) - Shows the actual number of votes followed by the number of votes as a percentage