Trouble with Grain Texture

I recently learned how create a grain texture on top of a gradient. My process is as follows: I created a gradient in a rectangle, then pasted the same size rectangle on top of the original. I changed the color of the top rectangle to a grey color (the color I want the grain to be), and then Appearance > fx > Texture > Grain. In the new Grain window that pops up, I set my specifications. When I get back to my artboard, I set the transparency of the Grain to "Soft Light." Once I do this, I have my desired grainy look on top of the gradient shape. Voila! I was so excited. 

Now, the problem comes whenever I try to move the grain texture in any way. It re-does the Grain process and is quite frustrating. I've included a screenshot where I'm in the middle of trying to move my shape, but the Grain window pops up to re-do it.. Am I supposed to "lock" the grain in place? It's almost as if I missed a step to finish the process because it keeps re-doing the grainy texture even though all I'm doing is moving the shape within my artboard.