Archives in header

@kozer: To change the text Archives
Go to => Appearance => Customize => Theme Options => Homepage / Frontpage Option => Posts Page Header Text => Edit the text and Publish.

To hide the single post title and date
Go to => Appearance => Customize => Additional CSS and add the following CSS Code.

.single-phort_post .section-title-wrapper, .single-phort_post .site-header-text {
    display: none;
}

Let me know if this works out!
Kind Regards,
Skandha

@kozer: Hello there,
You will need to select your homepage as a static homepage and then select your Homepage and Blog Page.

Now when you
Go to => Appearance => Customize => Theme Options => Homepage / Frontpage Option => Posts Page Header Text => Edit the text and Publish.

You should see the change. Maybe you had not selected a Blog page earlier thats why the change was not showing up.
Let me know if this works out!
Kind Regards,
Skandha

@kozer: Hello there,
You will need to Select a Posts Page for the option Posts Page Header Text.

Let me know if this works out!
Kind Regards,
Skandha

@maderas: Hello there,
To change the title of Portfolio Archive Page
Go to => Child Theme folder => functions.php and add the following Code.

add_filter( 'get_the_archive_title', function ( $title ) {
    if( is_post_type_archive('jetpack-portfolio') ) {
        $title = esc_html__( 'Portfolio', 'catch-sketch' );
    }
    return $title;
});

Now, Replace the text Portfolio in the code with the text of your choice.

Let me know if this works out!
Kind Regards,
Skandha