When I change the duration or start date of an activity, is it possible to move the later activity together?

Yes, it is possible.

By setting “Move with Succeeding Bars” to ON, when you move a Bar, a series of Succeeding Bars connected by Constraints can also be moved in conjunction while maintaining their order and duration. 

You can switch ON/OFF of “Move with Succeeding Bars” with the button on Toolbar.

[State in which Move with Succeeding Bars button on the Toolbar is set to ON]

[When a Bar is moved, the Succeeding Bars connected by Constraints will also move together]

By using Move with Succeeding Bars, you do not need to manually select multiple Bars, and you can easily adjust the schedule of continuous tasks.

What is Constraint? 
It represents the execution order for Tasks and their dependencies (such as activity B can be started when activity A is finished, or activity B can be started when activity A is started, etc.). In ACTY'S, it is expressed as an arrow connecting Bars.

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