I have a MIDI melody in 1/4 notes and want to double the lengths of the notes and move the start-times so that I end up with the same melody, but in 1/2 notes. Does Cubase 10.5 provide a way to do this?
MIDI>Logical Presets>standard set 1> half tempo. You may have to adjust note lengths. There’s a few different ways to accomplish this: the easiest being to select all in the key editor and drag right.
Not in the Key Editor on MIDI Events like in your gifs. Do it in the Project Window with the MIDI Part - that is the entity you want to stretch, not the individual Notes.