why cant I attach documents in yahoo mail? or even delete emails?

Hi there, I have not been able to use attach file in my yahoo mail account, and when I try to delete the emails I don't want I have to click at one by one, it seems the buttons for this features are not there. I notice this after an upgrade if the mac software.

How can I get it to work? could you email me back? I am in desperate situation here! I cannot attach anything!!!!

thanks