If your Salesforce instance is using a different language, you may notice that logged calls show under open activities on related records such as Contacts, Leads or Accounts.
An open activity has a field named “Status” which has a value from a picklist: https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_objects_openactivity.htm
This value has a property called “Closed” which tells Salesforce if that value is considered to be closing the task.
To check and update the picklist configuration you have on your Tasks object:
– log into Salesforce as administrator
– find the “Setup” link in the top right corner
– look for the “Customize” menu item under Build in the left-hand panel
– find “Activities” and select “Task fields” in the submenu
– find and click on the “Status” field name
You should be able to edit the closed values there.