Hi sandykoufax, hmmm yes it's supposed to write the [Undo] section when the program shuts down. Maybe something is not shutting down properly anymore in v4, I'll take a look.

But yes if you don't have it you can add it in at the end, the default settings are:

[Undo]
MaxMemorySizeMB=20
MinNumberOfUndos=10

You can bump up MaxMemorySizeMB by quite a bit. Then the way it will work is it will keep at least 10 and keep more than that if the total amount of space for undo objects is less than MaxMemorySizeMB.

- Michael