Skye,

If your chapters are separate files, then you should be using the
$chapnum variable and control that at the book level.

If all of your chapters are in a single file, then you have to define
your autonumber sequences to use the matrix method and have the
chapter number paratag reset the sub-ordinate paratag autonumbers.
This is explained in the "Using multiple counters in an autonumber
format" section of the Help file.

The first method is the easiest to use and maintain.