How do I force the next pictures number to be nnnxxxx?

If you want to increase the folder number, make sure that the currently used folder contains a file whose image number is 999. You can do it by renaming an existing file or copying a new one. Next, create all the _PANA folders up to (nnn- 1). The next image number that the FZ1 will record will be nnn0001. If you want to decrease the folder number, perform a similar procedure but continue creating folders from the currently used one up to 999_PANA. That will cause the folder counter to wrap around. Make sure the folder you wish to use does not exist (it will be created when you take a picture). If you want to increase the image number in the currently used folder, make sure that the highest image number in the folder is (xxxx- 1). The next image number that the FZ1 will record will be nnnxxxx. Hans-Georg Michna has some additional information on changing the picture counter here.  more