A sub-site set as primary site

Hello Sirs,

I need help on something that I just noticed.
One of the sub-sites, on my WordPress Multi-site, is set as primary site. It is visible on the "Dashboard > My sites > Primary site" page of all sub-sites (inc. the main site).

I don't know when and why I did that if I did it at all.
For that reason, I am wary if changing that could impact something somewhere. (Like, the Google Adsense registration, for example).

Is there any log where I can see the data I made that?
Or can you advise me based your experience and expertise?

Regards,

P.s.- I granted access to dashboard in case it helps.