How to prevent buyers changing my preferred shipping selection?

[pr-122677]

@links to members 

I have selected shipping on my items advertised yet the shipping is changed by buyers to a method not relevant to the package.  One person selected media mail and the package was 14"x7"x7" and was not media.  How do I prevent that.  Did I inadvertently select an option I didn't understand?  Thx in advance

[rock.star · Accepted solution]

Buyers can only choose from the options you provide. You listed the lamp with Media Mail shipping. 

[pr-122677]

I figured it was something I did, lol, my bad.  You are awesoem

[kensgiftshop]

The lamp, Media Mail was the only shipping option you offered on the listing.