Help for ACF update_field() for image

Hi experienced Envato authors,

It’s Tayfur from themezinho. I just looking a help for ACF update_field for image. We use ACF for our THEME OPTIONS and after import demo we set fields for ACF using update_field. I get able to update “text-select-option” but i could not set image field

I used something like this but it did not work.

$field = ‘preloader_icon’;
$attachments_id = 39;
$post_id = false;
update_field($field, $attachment_id, $post_id);

normally we use for update_field

update_field( ‘navbar_button_label’, wp_kses_post( “GET A TICKET” ), ‘option’ );

for image we could not set. We like to set image field from imported media library. I got image ID no = 39 but I could not make it,

Is there ACF experienced author able to help me out about this request ?

thanks for all