i've been always using the normal crusting buttecream but this time i wanted it to be more spreadable so i added milk to it but i think i added slightly more than i should as it did not crust only a little bit. how can i make my buttercream crust again? do i just add more icing sugar?

the recipe is 1 cup of butter 4 cups sugar, 1 tspn vanilla 1/4 cup milk.

There are many amazing b'cream recipes available. Trying to fix it *might* work but why not try one that you know will work great?
You will throw the whole thing off just adding more sugar. Any recipe that has more sugar than fat will crust.

the problem is i NEED to fix it as i have done a large qauntity of it. i've always used this recipe and have had no problems with it i just thought this time i wanted it slightly softer bc to ice my cake. please someone say there is a solution! its a shame and a waste to throw it away.

Just add powdered sugar about 1/4 cup at a time with the mixer on slow speed until it gets back to your normal consistency.