Schedule change - adjusted time

Back after some long time I found what I cannot understand.

I set new flight to departure at 2:00, which makes arrival at 4:00.
Then I decide to change the departure to 1:00, but the arrival remains at 4:00.
Which makes the flight time 3 hours and out of aircraft performance!

Should I all the time I change departure time press button “Reset all to optimum speed”?

You need to uncheck “Fixed Arrival Time”.

In time I scheduled the flight it was unchecked.
Why is it then this line “checked”, when I want to reschedule the flight? Why should I waste my time to click on something totally useless?

What is the point of this, for me, new feature?
I really do like when devs completely fuck up something perfectly work for years. And this happens every day.
Here I have luckily choice not to be part of it and do not pay for it…

Well, it’s great that you luckily have a choice.