Hello,
To achieve this you need a condition which is true after the channel value has changed.
The Global Conditions in DC don't have a 'changed by' operator but you can achieve this by using a delay filter. 1000ms seems suitable for the delay time.
- delay channel.png (74.81 KiB) Viewed 5269 times
You can reference the source channel and the delay channel in a Global Condition, the global condition will be true when the source channel and delayed channel are NOT the same, I set a result delay here so the overlay will remain active for 2 seconds after the origin channel and delay channel are equal.
- overlay condition.png (68.6 KiB) Viewed 5269 times
Once you have this condition you can configure it as the switch channel for an overlay.
I have attached an example DC project with this all configured for you to take a look at.