PHPBB3 / Register user nickname in utf-8 (arabic)

iv been trying to fix this issue for the past 7 days now and i cant seem to get it worked right.

iv set my whole server /php files to utf-8.
even configured apache to be utf-8

when someone is creating a new account he is required to enter forum nickname, if he enter utf-8 nickname he wont be able to login in phpbb3 and its going to show ?@#invalid charcters for him in mysql database and i have to edit it manual.

iv posted on phpbb3 forum
http://www.phpbb.com/community/viewtopic.php?f=71&t=2146668&p=13090313#p13090313

anyone have a clue what i need to do?

Forms
One often neglected method is ensuring that the data the server gets is UTF-8 encoded. One way to try and do this with HTML forms is to include the accept-charset attribute in your form tag. I say “try” because it’s just a suggestion to the client which submits the form. Be aware that some clients may not pay much attention to the attribute, especially older browsers. [Thanks to Alejandro for the heads up :-)]

how can i add this code to be used for the entire post actions in zen cart? or perhaps on create account (forum nickname)

or how can i merge it in

label class="inputLabel" for="nickname"><?php echo ENTRY_NICK; ?></label>