- Verify the font type used in the presentation and make sure it contains the desired symbols.
 - Check to see if the font used supports the inserted symbols.
 - Ensure that the presentation is compatible with the program used to view it.
 - Check the presentation’s code and formatting for any errors.
 - Check if the presentation settings allow for symbols to be displayed.
 - Update software applications that may be needed to properly view the presentation.
 
