Prev Next frame by frame

Hello again,

I have a Previous < and a Next > button on my movie.
I have content in each frame of my movie.

I’m trying to go back and forward from each frame…

as you can see in my code below, I was able to move to the following frame by pressing Next which is what I want. But when I press back, it goes back one by one until the very first frame.

I just want it to go back one previous frame, not all of them!

Please help.

movieclip.prototype.playBackwards = function(arg){
if(arguments.length>0) {
this.onEnterFrame= undefined;;
} else {
this.onEnterFrame = function() {
this._currentframe == 1 ? this.gotoAndStop(this.nextFrame) : this.prevFrame();
arr1_mc.onRelease = function() {
arr2_mc.onRelease = function() {