[TYPO3-english] How to prevent RTE HTML code-changes?

[FRANCISCO JAVIER MONIZ JULIA]

Hello all , I am trying to avoid that "tinyRTE (tinyrte)" Changes the appearance of what is being paste from a word on to it. I am not talking at first instance, but right after saving, the for example , just centered paragraph ,I save and ... it returns to its right justification by art, or when you set <br> and it changes them or adds <p>.
What I would like is to avoid or to know how to control this "html parsing" which is out of my control.

Thanks in advance for your time.