change a part, starting from a set

[giulio1993]

Good evening, everyone. I am in the condition for which I am comfortable to change a part that is present within a set. to do this I tried, within the assembly environment, to act on "model" and then I designed my feature, for example a hole. the problem is that even saving, if I go to open the single part, the new feature is not there.
How can I solve the problem?
Thank you for your attention

 

[Prof.]

It's likely that you created the hole at the level of the joint. to do so in the part you have to select the part and make active (green star). In this way you can work in the part even if you see the rest of the aid.
Bye.