What software do I need to modify PDF files?

I keep buying software thinking I can modify PDF files but I still keep coming up short. Either that or I'm too damn stupid to do it.

I have Photoshop CS6, Adobe Acrobat X Pro, Nuance PDF Create Assistant and I still can't figure out how to do it.

Seems Omni Page 18 Pro will at least convert it but not without problems.

Surely there must be something simple out there?

Open the PDF file, click the text to change it and save it...?

Thanks

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George - GeorgePics.com