How to change default dataset file?

I have a few datasets hosted, for example:

First shows nicely, as the CSV file. For BACE, I also added a second JSON file with recommended split indexes. However, the CSV file for BACE is still the main file, and it should be shown on the page.

How can I specify which file gets shown by default in the dataset viewer, i.e. how do I specify the “main” file?

I think this part of the docs can help you: Configure the Dataset Viewer