Override the global publisher layout & Override the predefined actions - Button or Action missing in Publisher and Lightning Experience Action in the Layout

Override the global publisher layout & Override the predefined actions - Button or Action missing in Publisher and Lightning Experience Action in the Layout

Click on Override the global publisher layout and Override the predefined actions to view the action for customization

Quick Actions in the Salesforce Classic Publisher:

Actions in this section are currently inherited from the global publisher layout. You can override the global publisher layout to set a customized list of actions for the publisher on pages that use this layout.

Salesforce Mobile and Lightning Experience Actions:

Actions in this section are predefined by Salesforce. You can override the predefined actions to set a customized list of actions on Lightning Experience and mobile app pages that use this layout. If you customize the actions in the Quick Actions in the Salesforce Classic Publisher section, and have saved the layout, then this section inherits that set of actions by default when you click to override.

Visual: https://www.youtube.com/watch?v=xQBik-cl9_g