While Simon's idea to use custom presets, that presets is perhaps the best way to enhance your JOSM experiences, it might be a bit intimidating.
But you can remember the keys over a restart. See the instructions on the [Add Value Dialog](https://josm.openstreetmap.de/wiki/Help/Dialog/AddValue).
Right-click on the dialog and check the "Remember last used tags" flag.
p.s. I can't remember I did it like this, I probably switched one of the variables in the settings pane under preferences by hand.