After I change the setting to Canadian TZ and hit OK, the Setting screen stays there. The Dashboard Window does shows setting change was attempted. The only way I can exit the Setting screen is when I press Cancel, and then it alerts that "Your changes have not been saved. Discard Changes?". Once I discard the changes, the App Setting msg in the Dashboard also disappears.
The reason I am attempting to make these changes is that the quotes are not updating automatically today using RBC as a source (for both US stocks - obviously but also Canadian stocks with :CA suffix). The reason I think is that since MT is set for US timeframe and with US Thanksgiving holiday, MT is not fetching the quotes. I am looking to test this assumption, hence while attempting to change the timeframes, I encounter the issue above.
BTW: As well, the data is not updating for the Canadian stocks when using Yahoo Finance as a source.