The solution is using Module Class Suffix. You can customize button, module content follow Module Class Suffix

E.g. Module Class Suffix: @bullhorn then:
- Class of button is 'fa-bullhorn'. If without @... the default is 'fa-pushpin'

Special positions are: stickyPanel, stickyBar, You can use them for any module type. For using this, please go to Module Manager and config your module to your desired position.

You can control module by:

• Go to Administrator » Template Manager » Your_Template » Tab: Tools utilities » Use Sticky SlidePanel (no/left/right)
• Go to Administrator » Module magager » Your_Module(by postion: stickyPanel)