Because of this change, not every account will show up when you search by name — it depends on each person’s privacy setting. We’re also working on a way to view profiles directly from inside a game, which will make it possible to send a friend request from there. That should be rolling out in the next few days.
In the meantime you can set your own Search Visibility to everyone and anyone will be able to find you and send you a friend request.
Modifying your Search Visibility settings requires StepSmash 1.3.0, which became available today for users on Android (iOS waiting on review from Apple). If you don’t see a Privacy button on your Settings page, double-check that you’re running the latest version of the app.