is there a way to change the black hand icon from the power switch or any trigger in the game to the one what i did?

Please post questions in the help section, not tutorial section. Also did you not even look at the tutorials in the very section you posted in? There's one for removing the black hand right here: http://ugx-mods.com/forum/index.php/topic,13695.0.html
Hope that helped.

sorry, i didnt know

but i dont want to remove it, i awnt to change it to one that i did

This topic has been moved to the Help Desk.

Yes, it is very easy.
You can set what to show in the trigger properties.
To do so, select the trigger brush, press 'N' to show entity info, then navigate to the key 'cursorhint' and set it to value 'HINT_NOICON'.
If you have a prefab, then select it, Right click > Prefab > Enter Prefab. Once done do Prefab > Leave prefab (after saving).
You can also stamp the prefab but remember that it will not be possible to de-stamp it, unless you create a new prefab.

But that's exactly what's shown on the tuto