Rendering midi files

Without reading the whole manual, I cannot find an obvious reference to an issue I recently hit. Whether it's in version 6, or has crept into 6.3.0, I find that midi files are rendered into wav files that set the highest volume to 1.0 in Audacity i.e. a decibel below maximum. This used not to be the case. For years I have been recording - and creating cds - for my own use when my arthritis finally catches up with me. In the case of, say, a piece where I redo a quiet ending, the two midi files would be rendered accordingly, e.g. take one at, say, 1.0 and the soft ending retake at, say, 3.0. Now the soft ending is rendered at 1.0, creating problems combining the two. In other words, if I recorded the Moonlight sonata movement by movement, the first movement's slightly louder passages would be rendered at the same volume as the loudest passage in the finale.

Is there an adjustment somewhere in the software? Or is it a new bug?