While scheduling a report, we have the option to click on share icon in the top ; Open sharing tab -> click on schedule -> submit the form. It creates an entry for the report in the scheduled reports table for a new scheduled job.
If we go to the report again, repeat the same process, make some changes in the form like Active = "false" and Run = "on demand", it will create a new entry in the scheduled reports table and will not modify the existing report.
Also, even if previously the report was scheduled as Active = "false", scheduling it again will show the Active = "true" in the form as a default value.
This is because it shows a new form and does not default from the last submitted form.
Also, as long as there are any entries for that report in the scheduled report table, the schedule tab will display a tick mark, even if the job is inactive.
For further modification of the schedule report settings, user can go to the scheduled reports table and modify from either opening the record or from the list view.