You have a couple options here. If you want the module on most pages but not all, you can check the display on all, then delete the module off of all the pages that you don't want it on.
If you want it on just a few, when you want to add the module to a new page, there's are radio buttons at the top of the control panel, you should choose the "Add an existing module" radio button. Then you can choose the module you want shared content from.
Also, when you create a new page, there's a Copy Page section, and you can choose to copy or reference module from another page from there. Reference is what we're talking about above; copy, if it's available, just starts you out with the same content, but the content in each module can be changed independently of each other (i.e. it's not linked in any way).
Hope that helps,