Change the view of open and closed activities for a client

Change the view of open and closed activities for a client

How can I change the view of open and closed activities for a client?
The current view for Open Activities:
Subject Activity Type Status Due Date Start DateTime End DateTime Owner Name Modified Time
In this view, I may want to remove the field "End Date Time" and replace it with another attribute (field) from the client task.

The current view for Closed Activities:
Subject Activity Type Status Due Date Start DateTime End DateTime Call Start Time Owner Name Modified Time

In this view, I may want to remove the fields "Start Date Time", "End Date Time", and "Call Start Time"  and replace them with another attribute (field) from the client task.

Some of the fields are defaulted values that we may not use; becoming clutter on the screen.