In general, there are two modes of every single track: Linear Mode and Musical Mode. In Cubase, the default settings is the Musical Mode, in Nuendo the default settings is the Linear Mode.
When the track is in the Musical Mode and you change the tempo. All Events starts are kept at the same Bars+Beats position, and the time changes. When the track is in the Linear Mode and you change the tempo, all events starts are kept at the same time position, and the Bars+Beats position changes.
You can switch the Mode for every single track independently in the Track Controls. The Musical Mode = orange note symbol. The Linear Mode = grey clock symbol.
I hope this is you are looking for.