quotation mark problems

Hi,
I’m using the last theme of Customizr.
i’ve a child theme, of course.

So, my problem is that :
When someone reply or create a topic on my forum (https://venenum.be/forum/) and customize the format, there is a problem because the theme remplace ” by ? (exemple: <p style= ?text-align: center; ?><span style= ?color: #ff0000; ?>-‘e-</span></p>) so we can’t see the correct format of the post.

I tried to fix this by adding this on my child theme’s functions.php

function replace_text($text) {
$text = str_replace('?', '"', $text);
$text = str_replace('?', '"', $text);
return $text;
}
add_filter('the_content', 'replace_text');
remove_filter('the_content', 'wptexturize');
remove_filter('comment_text', 'wptexturize');
remove_filter('the_excerpt', 'wptexturize');
remove_filter('the_title', 'wptexturize');

But it doesn’t work and i always see ? instead of ” …

How can I fix that please?

Sorry for my bad english .. Have a nice day and thank’s in advance ??