Not even sure about this because Apply serves a well defined function.
It is out of the Preset region to start with, and its purpose as we all know is to store the field we’ve just changed without the need to immediately click OK, in order that we can proceed with checking/editing other fields as well.
What could be done in the case that @Voxango presents here (changing preset from its comboBox) is Cubase showing a warning “Warning, you’ve made changes to the current preset that are not saved (applied). Continue?”, something like this, I think we get the point.
Generally, in the case that we want to “save as…” we can click “save” and we’re presented with a textBox which prompts for the name of the preset where we can actually write the one that we want, be it a previous one or a completely new one.