By default, checkboxes and radio buttons are displayed in vertical format. You can change the appearance to be horizontal instead using a Custom CSS Class.
The default vertical display is recommended. Horizontal display of options can be more difficult for users to read and interact with, and the layout of the individuals options is determined by the length of the options. You should only consider this if you are laying out a form in a traditional paper-based design for autogeneration of a PDF.
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You may need to adjust the width of the control to better fit the content.