How to change Http to Https in bulk via eBay
In our ebay account go to "seller hub" and choose all active listings
Choose the amount of listings you would like to change in bulk, 500 max
Choose all your listings by marking the top check box (1)
Click on the “edit fields” button (2)
Choose “item description”
Clicking on it will open a box with 3 options, choose "Find and replace"
In the "Find" box enter the word HTTP (1)
Enter the word HTTPS in the "Replace with" box as shown at (2)
And clicking save (3)
Click "Save and close"