Quick Actions fields in Ligthning Experience
|Knowledge Article Number||000239984|
|Description||Any new Custom field or existing Standard field on Task object is available in Salesforce Classic however you will notice this is not available in Lightning Experience.|
|Resolution||To make the Standard field or the Custom field visible in Lightning Experience, please follow the below steps
Switch to Lightning Experience:
1) Click on Setup | Select Setup Home | On the left pane, under User Interface | select Global actions
a) Click on the layout link right next to the action New Task.
b) Drag and drop the fields that you would like to add it to the Task layout.
c) Click on Save
Action Layout Editor