Uninstall previous version first?

I've just downloaded ver 0.9.6.3 but have not yet installed it. Should I uninstall ver 0.9.6.2 first, or can I install the newer one 'on top'? If I need to first uninstall the previous one, I guess I'll lose my preferences?

Sorry if this has been answered before, but I couldn't find anything about this in the guidance.

Thanks
Ian