When is hook_user_presave triggered?
hook_user_presave is an event listener that's called when a user account is saved.

It's invoked from user_save and shouldn't normally be called manually.

// Invoke hook_user_presave() for all modules.
user_module_invoke('presave', $edit, $account, $category);


If you want to save data on the user account, just use user_save