I don't know how your memory is, so you could start there and get rid of anything saved. Of course, if you have saved numbers that you want to keep, then you shouldn't do this.
2nd--> 6 (mem) -->F1--> 1 (Ram)--> 2(Default)
I've also read that putting the function as parametric function works.
You put your function in the y value and t in the x value.
Other than that, I don't know.