If you turn off Preferences / Layouts and Styles / Default Lister / Update Default Lister automatically when closing a Lister, it will stop remembering the last folder you were in.
If it's on, you can also turn it off via Settings > Set Lister Defaults, which is also the way to save the folder(s)/tab(s) you want to open in new windows when the option is off.
The settings under Preferences / Launching Opus / Startup may also be relevant when rebooting, if you don't want open windows to be remembered across reboots.