I can’t delete the background on the girl/palm tree/boat with select and mask - what’s wrong?

A1. Make sure you have a loose selection (with the lasso tool) around the object before entering select and mask. Then, check the smart radius option with full opacity. Use the refine edge brush tool and a relatively large brush to erase the background. Avoid erasing the same areas multiple times. Output settings should be on a new layer with a layer mask, so you can edit as needed. You may also need to do select and mask again.