How to Import Contacts, Activities etc. from 'Account' to a 'Potential' in the same Account?

There must be a way to import or move all contacts, tasks, Activities, Documents etc. from an Account or a different Potential to the Potential we want. A project is fluid, changes and re-assessment processes need to made easier.

For example, We have only an 'Add New Contact' or 'Add New Task' option. What if I have tasks that were made already and due to either human error or changes in project direction I want to now add it to a new Potential or Account? This is not possible without cloning each entry which is time consuming and inefficient.