Recently updated from 2013 to 2017, with an assembly open, i could modify a part and save it as a new part without it interfering with the assembly. In 2017 doing this updates the assembly with the new part. How can i change this back?
I'm not sure what method you're using, but when you open a component from an Assembly, then go to "Save as...", you should get the error message shown below. If you aren't, go to Tools > Options > System Options > Messages/Errors/Warnings and see if it's been dismissed.