Turn off autocomplete tab deletion in Intellij

Per @yole's answer, adding screenshot showing how to in Rider/IntelliJ to prevent tab from overwriting text. In Settings, change the editor actions for Choose Lookup Item and Choose Lookup Item Replace:

If you select from the autocomplete dropdown and press [Tab], the the selection replaces the following text.

You have to use [Return] to accept the autocomplete to have it inserted.

Does pressing enter key instead of tab key works for you?