object mode outline changed issue

hello. i just have an issue here.while i was modeling my guitar and it was in object mode, i accidentally pressed something on my keyboard and now my object mode doesn’t have that yellow orangish outline it suppose to have.the outline now is green. can you be kind and tell me what i have pressed to cause it to turn green so i dont do it next time, what is it for, and how can i turn it back to its original object mode color. thanks and god bless

Sounds like you added it to a group (ctrl-g, possibly). Try ctrl-alt-g or ctrl-alt-shift-g to remove it from the group.