I use Edge and haven't got a 'toggle to save' box in the right-hand corner of my screen. When I sign in to anything new I get a pop up offering to save the password. She can go into settings on Edge ( three horizontal dots in the Right-hand top corner of the screen -scroll down to 'settings' click and then choose 'password's' with the sign for a key then make sure the toggle for 'offer to save passwords' is turned on. When this is done the passwords should be saved automatically, and she will be asked , by way of a drop down box, when any new ones are created if she wants to save them.