If you have 10,000 ancestors and cousins in your tree, how would you propose that they be "on the screen". Do you mean in list? Or in trees?
If you want a list, that is what the index is for. That's the list of people in the left panel of your screen when at the family tab of the People Workspace. You can sort people by last name, first name, date of birth, marriage or death. You can also filter for places or text strings in various fields.
If you want a report for everyone in your file, there are several:
1) The Person Reports > Index report
2) The Charts > Extended Family Chart - includine everyone in file option. This shows everyone in trees. If you have a lot of people (over 10,000 or more), this report might take all night and take more memory than you have.)
3) A Person Reports > Custom report showing everyone in your file.