Morphing proving itself a challenge, help needed please

In Scene 1, I’ve only got a button in frame one (“morphbutt”).

This button has two layers. Layer 2 (on top) has a key frame in the “up” frame and layer 1 (on bottom) has a key frame in the “over” frame, frame 1 is a clear keyframe.
Frame 1/Layer 2 has a blue ball (graphic), Frame 2/Layer 1 has the same blue ball (movie clip). This movie clip shape-morphs the blue ball into text.

The question is, how on earth do I prevent looping the morph and having it play only once whilst the mouse is rolled over it? Right now, as long as my mouse is over the blue ball, it keeps morphing over and over again.

Any help will be much appreciated as I am still a novice trying to learn Flash MX Pro at home by myself.