Thank you for the information, now I see. Unfortunately, currently there is no way to change interval display number. The suggestion to implement this possibility was registered and your query is added to it.
At the end of the day, the important thing, Constantine, has been to report this for future upgrades, since this is a basic feature found on alternative suites.
I understand that this feature is still missing as of v9.2.1.43 (x64 deb). I think it is an important feature when working with charts. Is it in the roadmap yet?