There are good amount of migration plans and Reports | Audit Logs page stays running for hours. You are able to download the reports but sometimes fails.
Delete plans that are no longer in use.
Have an individual customer account for each of separate site migrations by going to https://portal.ondemand.quest.com/customer/new/
This will prompt you to enter a new Company Name. Once configured, the Company Name when logged in to the tool will become a dropdown from which you can select the configured customers. Once the subscription is configured, the new Company Name will become usable.