I was playing around with tradingview and they announced a new feature on Dec 8 to add a small icon to the bottom of the chart to show when the continuous contract switches over Than I looked on TOS to see if they have something similar and they do It's a vertical line that can be added using the settings I think it was on but using the 1 min I think it was off the screen by the time the market opened At least I will probably know the next time it should be near the middle of the month
There is another setting which is the "Start aggregation at market " which I am not sure what it's supposed to do which seems to be cancelled or grayed out when I check the "Show extended-hours trading session" but that is also on the equity and options tabs not just the futures