two diffrent fonts colliding on the same text box

I would second Ricks suggestion. Such behavior indicates that the fonts are differently encoded/ do not have all the characters or that one of them is a "bad" font that has technical issues or is poorly designed. Try typing everything in one font. also of course check whether you have any stray source text keyframes on the timeline that may override your newly input text and still hold old information.

Mylenium

Try entering all of the text using one font. When the Text layer is complete, select only the characters you want to change and choose a new font in the Character Panel. That is the same workflow you would follow in MS Word, Illustrator, or Photoshop.

You could also start entering characters without clicking anywhere else, use the Character Panel to change fonts, and continue typing.

The only way to get the behavior you describe is to exit the Edit Text mode by clicking on the layer in the timeline or changing tools using the toolbar.