Thunderbird installation is not clean. There are always rests of old installation. How can I solve this Problem?

There are always rests of old installation. How can I solve this Problem?

You'd need to explain what 'rests of old installation' exactly means. And how is that a problem? What are you trying to achieve in the first place?

Sorry for my mistake, I don´t mean Thunderbird rather Firefox. For examble I use REVO Uninstaller to monitor the installation. When installing ends with a new version there is still the elder one registert. And it´s not good to uninstall the old version because the new one is than demaged. I hope you can help me. And sorry for my english. Other software products make a clean installation. Thank`s

moving this topic to the Firefox queue