this is probably something simple so i'll explain in short :
after extruding , if a delete this face(pic 1)
you can clearly see that the face where i extruded from disappeared(pic 2)
basically i want to have both picture 1 face and picture 3 face when extruding but instead i get 1 and 2 .
Thanks in advance .
Note : i used to do this 2 years ago (i can tell because i've loaded some of my models from 2014) but i can't remember how i did .