Change start of week day in Lightning calendar

Read numerous forums re Lightning in Thunderbird 60.4.0 Lightning does not keep the starting day that I choose, that is Sunday. Ubuntu set at locale frCA time zone Toronto. How to set week start at Sunday for ever. As per Geckozone it is strange that second choice is root. If I choose root date format changes to yyyy/mm/dd and problems occur with time setting for event. I should see French CA, but the French on picture is for French FR. How to change setting for proper Locale