Show us the project, the setup, some screenshots, the export you already did. This could be many things..
If by this you mean that it's a video file, you are stuck. Sorry.
If you mean something else, like you're using a template, please go into detail. And yes, screen shots do help. Don't skimp -- show the entire user interface revealing any properties you've keyframed or modified.
This might work. Precomp your entire composition. Then scale the width to -100% (width only). Then go into your precomp and do the same for all the text layers.
Sorry for this issue. Did you ever find a solution? Please let us know if you have or if you still need help.