You can find this option by this path Design tab -> Popup Location tab -> “Enable Layered PopUp Style”. By default all PopUps have modal style: it appears on user screen over the whole site. Layered style allows you to show your PopUp – on selected position: top, bottom, etc. and not over your site – but right near your content.
Just check the examples of such PopUps on this page below. This feature are included in PRO version of PopUp plugin.
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