Edit the layout of activities to add or remove fields on New Task, Log a Call, and New Event activities. Find activities on the right side of your referrals, intakes, and matters. Customize each layout to streamline your business processes for all users.
Let's add the Document Link field to the Log a Call activity, so users can directly link any related documents when logging a call. Follow this guide and add any necessary fields to your layouts.
1. Click the icon in the upper-right corner and click Setup.
2. In Quick Find, search for "Global Actions" and click Global Actions.
3. This page contains all of your global actions. Locate the action you want to edit, and click Layout next to the action. For this example, click Layout next to the Log a Call action.
3. This page contains the current layout of the selected action. You can add any field from the Task object to your layout. Drag the Document Link field from Task Fields onto the page layout. Save the layout.
4. Hover over the field and click the minus icon to remove it.
5. Navigate to the activity tab and review your changes.
See Salesforce documentation for more information.