like, whats the best way to do it
I'm not sure if this answers your question, and I'm not sure if this is the best way, but this is usually what I do:
I have a specific folder where my Decker files live, and there's a "Decker" folder inside it, which is where the program and the official example decks are.
It's something kinda like this:
C:\MyDeckerFolder\Decker\
When itch.io lets me know there's a new version (on the feed or by email) I download it and copy the "Decker" folder from inside the zip file and then paste it into "MyDeckerFolder" so it overwrites the existing "Decker" folder with the new version.
This way my shortcut to open the program still points to the same location.
But on the other hand if you've been making your own things with the example decks recently (Like creating fonts with the font editing deck) then you'll want to copy those specific decks to another place first, so they don't get overwritten.