Amber I use butterflavored Crisco, or butterflavored crisco baking sticks and makesure they are at toom temp. Bakingpowder will make them rise like a cake,so make sure you using exact measurements and are you useing self-rising flour?? Use regular flour(not self rising) I always measure out flour after it has been sifted and incoperate it into the creamed shortening and sugars, it helps if the eggs(if called for) are at room temp too,)
If the reciepe calls for 8 minutes for baking I take out Just before that or untill the edges are golden brown only! That way they remain soft and chewy it appears the center of the cookie may not be done but it is,, let it cool a couple of minutes before removing from the baking sheet ..Put cookies in an air tight container with a slice of apple and this will keep them chewy , but change the apple slice every couple of days.
These are the only things I can think of that may help!