ut how does it go in the other way?

my code for more buttons currently looks like this

add_filter( 'wpforo_editor_settings', function( $settings ){
if ( empty( $settings ) || ! is_array( $settings ) )
$settings = [];
$settings             = 'compat3x,fullscreen,hr,paste,textcolor,lists,table,visualblocks,visualchars,insertdatetime,charmap,searchreplace,anchor,advlist';
$settings = 'fontsizeselect,bold,italic,underline,strikethrough,forecolor,bullist,numlist,hr,alignleft,aligncenter,alignright,alignjustify,link,unlink,blockquote,pre,wpf_spoil,undo,redo,pastetext,source_code,emoticons,fullscreen';
$settings = 'cut,subscript,superscript,outdent,indent,backcolor,removeformat,table,visualblocks,visualchars,insertdatetime,formats,charmap,styleselect,fontselect,searchreplace,anchor';
return $settings;
});

toolbar 1 standard buttons
toolbar 2 new Buttons

remove buttons you don't need

the missing TinyMCE plugins you have to add under
wp-includes > js > tinymce > plugins

so that the buttons are not displayed in the signature editor, add the empty toolbar2

		/**
		 * start init tinymce settings
		 */
		$wp_editor_settings                        = WPF()->tpl->editor_buttons();
		$wp_editor_settings = 'bold,italic,link,unlink,undo,redo,source_code,emoticons';
		$wp_editor_settings = '';
		$wp_editor_settings             = '';

wpforo > classes > member.php

https://wpforo.com/community/postid/47409/

That's what I found, how something is removed. But how does it go in the other way?

So i'm very pleased, if you will give me a lift

the open source plugins for the editor you can see here > https://www.tiny.cloud/docs/tinymce/6/plugins/
you can activate all of them for wpforo
if there is one for your purposes you have to test
maybe the template plugin

I'd like to ad two buttons to have easy access for shortcodes. So the buttons "only" need to paste some fixed text o - when it's possible - the current user-id.

I'm familar with adding via functions.php. I've found a solution here to eleminate some buttons.

So i'm very pleased, if you will give me a lift :-)

what function are you missing in the editor
you can add this via the functions.php of your wp-theme
example see attachment

i have tried div. things, but i get no success with the mentioned plugin with the current wpForo and no matter which theme (2022 or Classic) and no matter which layout.

Has something changed after all?

We hadn't checked this plugin workability, so you can try yourself.

in Dashboard > Plugins > Add New, Search for TinyMCE and in the list you can try to find a plugin which will make the TinyMCE editor More reacher.

wpForo editor is the same TinyMCE editor, it'll not be changed in 2.0 version,