I don't find how to change the font size when I print labels (I have a CiviCRM Spark account). The default size is far too small and the Post office don't accept it...
Yes there is a option to change the font size. The UI setting is not user friendly but it does allow you to update the attributes.
- Navigate to CiviCRM >> Administer >> System Settings >> Option Groups.
- Find for Mailing Label Format.
- Click on "Edit options' link besides 'Mailing Label Format'
- You will see list of formats, click on 'Edit' besides one of the format type.
- In 'value' text field find for 'font-size' and change the value from old to new
for eg if the old value was
"font-size":8 than replace it with