I am creating several similar assemblies. The assemblies use parts that are not in my current version of solidworks which is 2018. When I only one particular assembly open, I saveas and give it a new part number. Then it asks me how I would want to save the older version parts (saveas, save and open, etc). I don't want to save those old parts in 2018 yet. How can I stop this behavior? It is a recent occurrence.