Change quote to &laquo; &raquo; I'm using Drupal 7. A lot of text are using quotes like "text" or «text».
I want that for all older text on the site as well as for new text there will be one type of quotes used: «text». 

Can you help me with that? Maybe some text filter or module can do this? Tnx for advice.
You can try this module:

Custom filter


  This module allows you to create content filter using regular
  expressions. Instead of creating a new module for each filter you
  need, now you can easily create and organize your own filters. Your
  filter will appear in the input format configuration page.


Pattern: /([^\"]*)\"([^\"]*)\"([^\"]*)/i

PHP Code: do not tick

Replacement Pattern: $1«$2»$3

REMEMBER to flush the cache!

ALSO note that this pattern could wreak havoc with tag attributes. So you will have to expand it to exclude quotes surrounding attributes. But that is a question for stackexchange.com.