Legacy setup: The automatic per-user-view migration described by this article is not available in the current guided Portal setup.
Instead, create or prepare a Users Table in Airtable, with one record per user and a suitable login field. Add a linked-record field from your data table to that Users Table and link each record to the users who should see it. Existing filtered views do not replace these user links.
Then create a Portal, choose the Data Table and User Field, and complete the login, profile, record-creation and form-field steps. See how to set up the Users Table.