That’s strange. What value was selected as the interval?
“1 Day Before Listing Renews” is the default option as far as I can tell. Like many of the other listing settings you can’t change the default value but what you can do is to create a “master” template that holds all your preferred settings. You can define the master listing in the GarageSale preferences > eBay > New Listing as you probably already know:
https://manual.iwascoding.com/gs8/en/GarageSale_Preferences-eBay.html
Another way is to simply create a duplicate of that master listing manually.
Hope this helps,
Kristian