The newest version that works with win 7 is 115. This link will take you there. https://ftp.mozilla.org/pub/thunderbird/releases/115.18.0/ select whether 32 or 64 bit, and then select preferred language. You can uninstall current version, but keep the profile After installing the newer version, you will need to update the addressbook. click tools>import>import a file and follow the links for addresssbook and select the MAB option, and then select the abook.mab from the profile. repeat the step with the history..mab from your profile. This URL can be helpful in orientation to the newer release: https://support.mozilla.org/en-US/kb/getting-started-thunderbird-main-window-supernova

The following link might be helpful: Upgrading from an older version of Thunderbird https://support.mozilla.org/en-US/kb/upgrading-older-version-thunderbird

Quotation from the above link:

During a version upgrade, some versions of Thunderbird perform data and other conversions (for example address book data) to enable new capabilities. If you skip an important version, then Thunderbird may not work, you may have missing or incorrect data, or other complications may occur. To avoid this, closely follow these directions.