Navigation voice settings should be persistent.
More often than not, I know where I'm going, but would like to know about traffic incidents/alerts. As such I like to use waze in alerts only mode. However, every so often, waze will decide that it will turn itself back to full voice navigation even though I did not select that. I do not know what triggers it, but it does continue to happen. Just when I think it's going to stay, the settings get switched. It's quite annoying that it can't keep a setting.