TinyMCE Advanced newline problem

1) use soft returns (shift+enter) to insert <br> instead of paragraphs.
2) if you want to make intent in the beginning of sentence after
(SHIFT+ENTER), then you may need to use this custom code: https://wordpress.stackexchange.com/a/139347/42702

Go into Settings -> TinyMCE Advanced, and check the option Stop removing the <p> and <br /> tags when saving and show them in the HTML editor. This will allow you full control over those tags inside the HTML view.

For a single line break without overriding the editor, use Shift+Enter.

To override the editor and make Enter a single line break, put this into your functions.php:

function change_mce_options($init){
    $init["forced_root_block"] = false;
    $init["force_br_newlines"] = true;
    $init["force_p_newlines"] = false;
    $init["convert_newlines_to_brs"] = true;
    return $init;       
}
add_filter('tiny_mce_before_init','change_mce_options');

This does not convert shift+enter into <p></p> however, and this will cause some strange behavior for already existing content (if you're inside an existing <p> it will give two lines instead of one), so I would strongly recommend getting used to shift+enter instead.