A head-mounted-display system may include 1) a support assembly and 2) a pair of display assemblies moveably coupled to the support assembly such that the display assemblies are moveable between a plurality of positions corresponding to a plurality of user interpupillary distances, with the pair of display assemblies respectively defining separate viewing regions for a user's right and left eyes. Each of the pair of display assemblies may include a lens and a display screen. The head-mounted-display system may also include a detection subsystem having 1) at least one position sensor and 2) a determination module that determines a positional relationship between the pair of display assemblies based on measurements obtained by the at least one position sensor. Various other methods, systems, and computer-readable media are also disclosed.