To know all the companies you have assigned, go to the Lists section, COMPANIES tab and click on FILTERS.
Click on the field Assigned to and select from the drop down menu your name.
Click on APPLY FILTERS.
The list will show the companies assigned to the selected user.
To have available this list in the future, click on SAVE, Save As...
A menu will pop up, fill in the name of the new list and choose if you want to see it only you or the rest of the team.
You will be able to access this list on the drop down menu.