Changing The Phone Number In The Header

The header phone number is a WordPress custom menu item. If need to edit just the phone number, go to WP Admin > Appearance > Menus > Top menu. If need to customize the styles of the top menu, follow the next instructions:

Go to WP Admin > Appearance > Headers/Footers > Header - Default Design, and open the header in the Live Composer page builder.
Open the "Mega Menu element" options panel (click on the "cog" icon). 
Click on the "Styling" tab. 

If you are using the SEOWP theme version 1.8.7 or below:

All the top bar elements are menu items. To edit these items go to WP Admin > Appearance > Menus > Top menu. For other header customizations, visit WP Admin > Appearance > Customizer.