Unfortunately custom tab, which is added via Theme Options > Single Product Page, can’t be re-ordered using the code from the “Re-ordering Tabs” section of this documentation https://docs.woocommerce.com/document/editing-product-data-tabs/ . You need to edit the wp-content/themes/royal/woocommerce/single-product/tabs/tabs.php file to change custom tab order. Also in other way you can delete custom tab content in Theme Options and add it manually using the code from the “Add a custom tab” of the mentioned woocommerce documentation and set tab priority there. Note it’s strongly recommended to make such customizations using child theme https://codex.wordpress.org/Child_Themes
Thank you but I need to write custom text for each product, so woocommerce “Add a custom tab” doesn’t do the job because it display a tab with same content all around the website. So your theme custom tab is ok for me, could you help me to reorder it in the php file please?