  We present muon spin rotation and relaxation ($\mu$SR) results for
chalcogenide spinels CuCr$_2$X$_4$ with X= S and Se. Both compounds are known
as ferromagnetic metals with high Curie temperatures. Our $\mu$SR and
magnetization data show clear signatures for additional magnetic transitions
far below the respective Curie temperatures. They can be related to changes in
the Cr valence system from the mixed valence between Cr$^{3+}$ and Cr$^{4+}$ at
high temperatures with collinear ferromagnetism to a charge-ordered state at
low temperatures with a different ferromagnetic structure. Our results
demonstrate that the electronic systems and the related spin structures of both
compounds are more complex than assumed so far.
