Access versions fight over control of the registry.  So, the last version of Access you open takes control of the extensions it recognizes.  There are two ways to solve the problem.
1. Always open the version of Access you want and then open the database - awkward and not functional for users.
2. Always use a shortcut that specifies the version of Access to open followed by the name of the Access database - much more user friendly for users.
As the programmer, I work with too many applications to keep shortcuts for each of them so I use option 1 for myself and only keep shortcuts for the apps I use rather than develop.   So, the timekeeping app has a shortcut because mostly I will be using it rather than developing it.