Collaborative learning confusion

hello ,in collaborative learning assigment 1 ,why did I retrained whole parameters after adding new user column ,what I only need weights of new user ,have i misunderstanded anything

When you add a user, you need to re-train so their review can be included in the weights for making new predictions.

okay ,why don’t i used anyway to train weights only for the new user ,to reduce computationality ,save last info?

You get the best performance if all of the weights are computed including all of the users.

ok thank you