No setting/option currently. Sounds like a good potential enhancement though. Appreciate the question.
In the meantime, until the enhancement can be made available - you could try the following
1. Uninstall the old version (if unused). You then might need to set the new version as the default, by following the steps explained at the following site, depending on your version of Windows.
Windows 7:http://windows.microsoft.com/en-us/wind ... =windows-7
Windows 8:http://windows.microsoft.com/en-US/wind ... es-default
2. If the old version cannot be uninstalled (e.g. if still used) following the above steps to set the new version as the default might be enough to solve the problem, assuming you want to make the new version (2013) the default - for PowerPoint file types.
3. If neither of the above works, or is possible (E.g. to uninstall the old) , you can try uninstalling the new version (2013) and then reinstall it - and that should make it the default on your system.