Submenus

Import/Export Submenu

<?php
add_filter( 'ninja_forms_admin_parent_menu_capabilities', 'nf_importexport_capabilities' ); // Parent Menu
add_filter( 'ninja_forms_admin_all_forms_capabilities', 'nf_importexport_capabilities' ); // Forms Submenu
add_filter( 'ninja_forms_admin_import_export_capabilities', 'nf_importexport_capabilities' ); // Import/Export Submenu
function nf_importexport_capabilities( $cap ) {
return 'edit_posts'; // EDIT: User Capability
}

Settings Submenu

<?php
add_filter( 'ninja_forms_admin_parent_menu_capabilities', 'nf_settings_capabilities' ); // Parent Menu
add_filter( 'ninja_forms_admin_all_forms_capabilities', 'nf_settings_capabilities' ); // Forms Submenu
add_filter( 'ninja_forms_admin_settings_capabilities', 'nf_settings_capabilities' ); // Settings Submenu
function nf_settings_capabilities( $cap ) {
return 'edit_posts'; // EDIT: User Capability
}