I would like to know how to enable .htaccess for one account / domain only ? not for all if is blocked by default for all accounts
Do you want to enable .htaccess for one account or avoid blocking one domain via .htaccess, assuming all others are blocked? I'm not sure what you mean by your question so I would believe you have multipla domains pointing to a same webspace, in which case you can create a per-domain directory into which you can adde its own .htaccess with whatever rules you want to implement. Domain addon instead of parked if you would be using cpanel.
i mean no user / account has .htaccess enabled, users have .htaccess disabled for their accounts but i want to enable .htaccess only for 1 user / account