Just something not to forget - (save your current version of the videopad file of course).
Then 'export' your current version to say MP4
To avoid confusion - Close videopad.
Go to your exported file and 'open with' videopad - save under a different name.
You now have a 'totally cleaned up version', but with out the untidy bits - so you can now start editing again as you wish, without losing any effects of your previous edits.
I'm no expert - but it works for me!