How to get more zeros in filename?

I need to break up very long voice recordings. I’m doing it by detecting silences over a threshold. This only seems to work if there are less than 99 total parts. Once I reach 100 the filenames (and therefore playback) won’t be in order because 100 comes before 11. I can get the labels in the metadata to start at 001 by adding a # to the label text but I can’t find a way to fix the filenames.

In Analyze > Label Sounds, try changing “Sound ##1” to “Sound ###1” (insert an extra pound sign).