I have a problem about excel , hopefully you can help !

Normally , if one cell involved link with another cell , when i double-click
this cell ,it will jump to the related linked cell (i.e. set formula "=A2"
into A1 cell, if i double-click A1 cell, it will automatic jump to A2),
however, my excel loss this function, would you please advised some method or
setting to let it enable.