How do I edit text displayed on my browser tab?

You can either use this code in your function.php

remove_all_filters( 'wp_title' );
add_filter('wp_title', 'filter_pagetitle', 99,1);
function filter_pagetitle($title) {
    $title = get_bloginfo('name');
    return $title;
}

Or install plugin like Yoast SEO.

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EDIT : Screenshot

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UPDATE : Change header.php in your theme folder if above solution doesn’t work for you.

<title><?php get_bloginfo('name'); ?></title>