1. Download the project to your computer (click File > Save to your computer).
2. Show File name extensions in File Explorer (click View and check the box on File name extensions), then replace “.sb3” with “.zip” (like you're renaming the file).
3. Double-click the ZIP archive to open it (File Explorer can do this by itself, or you can use your preferred third-party program).
4. Find the “project.json” file within the ZIP archive, and open it too.
5. Press Ctrl+F and type “data_listcontents”, then click Find Next. Exactly what you type should be highlighted.
6. Right next to that, you should see:

"params":{"LIST":">list name<"}

Check the list name part to make sure you're looking at the right list data. If that's not the case, keep using Ctrl+F until you find the affected list in the file.
7. A little after that, you should see this part:

"width":0,"height":0,"x":7,"y":456,"visible":true

And the key parts are “x”:>number< and “y”:>number<. Try changing those numbers to something like 100.
8. Save (click File > Save).
9. After you're out of the project.json file and ZIP archive, set the file type back to SB3 (the same way you set it to .zip), and load up the project (use the Scratch app to check and/or go back to your current project on the website and click File > Load from your computer).