Align to center stage after resizing satge

Flash CC, last update, OS X 10.8.5

Hi!

How to change the size of the document can reset the central point of reference?

I created a 750x300 composition, now I wanted to reformat the size of 750 100, for this purpose, I used the document options cmd + J to change the size without resize.

Now align option "Align to stage" still moves objects by primal sizes. It does not help to save the document in a new size, re-opening?

I have no idea what to do, every object, move clip symbol instead of in the center of the page?

I can not find information in the documentation of Flash.

What I have to change except the size of the document to align referred to the new page size?

Best Regards!