Home screen problem

After updating my MacBook Pro (late 2013) to Mojave 10.14.1, I'm having two minor but annoying problems:

1) On the sign in screen, the desktop wallpaper no longer covers the whole screen - a thick band of black appears at the top. The desktop wallpaper is sized properly after I sign in.

2) Notifications that appear in the upper right are placed too far to the right so I can no longer see the Close or Delete buttons to turn it off.

Any solutions for these problems? Many thanks.