This might be a stupid question, but what's meant by mark and reinforce?Reaching over a dogs head is a threatening gesture, he's asking you not to do that. Instead try approaching him from the side and giving him a scratch behind the ear.
As far as teaching fetch, you might try getting him to target first. Targeting AKA "Touch"
And another thing my mom liked to ask.
She like to put an old thin blanket in his sleeping basket, but he always takes it out.. (and sometimes even 'rides' it.. )
How can we stop this behaviour?