STEP 1: How to edit the Menu widget?
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To begin, navigate to the Toolbar > Edit with Elementor > Header (the name of the template may be different)
Here, you can edit the Menu widget buttons and styles:
Check this guide for more details
https://elementor.com/help/the-menu-widget/
https://elementor.com/help/nav-menu-widget-pro/
STEP 2: How to edit the mega menus?
To access the mega menu content, click on the menu button and edit the widgets below:
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Check this guide for more details
https://elementor.com/help/create-mega-menu/