Cant change second admin language

Hi, for my german website, i’ve initially added through Polylang
– English
– Arabic
– French for customers to switch. ive added a new admin to my wordpress dashboard for my friend. She wishes for her WordPress dashboard to be Dutch. But because I have activated Polylang, it overwrites the WordPress General Language Options in the Settings –> General –> Default WP Language. Now i only get to see English, Arabic, French or German as WP Dashboard language. Im afraid to deactivate the plugin and loose my stuff or break the website. Ive tried adding Dutch in Polylang, but still that didnt appeared as a new language option for WP’s General Dashboard Language. Whatever new language I add in Polylang, nothing changes, its as if i had to start with Dutch too in the beginning because Polylang is overwritting my general WP dashboard options with the old 3 languages. What can i do. i would appreciate help.