Upgrading To The Current Version of UBB.threads 7
The upgrade path from UBB.threads 7.5.x versions, has always been to move to the most recent version of UBB.threads as they become available. Such as 7.5.x => 7.6.x. There is no need to do an incremental update from 7.5.8 to 7.5.9 to 7.6.0 to 7.6.1...etc. You should update directly from your current UBB.threads 7 version, to the most recent version of UBB.threads.
The UBB.threads 7 Upgrade Guide
can be found in the Docs
tab in the menu header.