That's a common thing: for one reason or another layer 3 doesn't have layer 4's speeds set as a standard... Just change the relative X and Y speeds to 1 in the layer proporites.

A reminder to clear all misunderstandings (ok, so I'm bored too, who cares )

Jazz 2 supports a total of 8 layers: 2 foreground layers (1 and 2), 4 background layers (5 to 8) and 2 player layers (3 and 4). In low detail, only layer 3,4 and 8 are shown.