You appear to be looking for a Path metaphor. "Changing the subject" is usually interpreted as changing the direction of a conversation. So any term that indicates motion along a designated Path will be interpreted that way.
You see it in taking a tack, which means altering the direction of a ship by maneuvering the sails, switching/shifting gears, which means altering the speed of a machine, often preparatory to altering direction, and in deflecting, which usually refers to the conversation as moving along a channel or road.
Get the metaphor set up in your mind and then use phrases that it suggests.
Maybe reading Lakoff and Johnson would be a good idea, too.