Complex sentence: It was originally announced that Lovato's second single would be "Who's That Boy" (which features Dev); however, Lovato later changed the single to "Give Your Heart a Break", officially announcing it on Twitter.
Split into simpler sentences: It was originally announced that Lovato's second single would be "Who's That Boy" (which features Dev). However, Lovato changed the single to "Give Your Heart a Break", was officially announced on Twitter.