Move default folder to external hdd

I need to solve a problem… I want to change the NextCloud default folder location in the external hdd from /nextcloud/files/admin/files to /documents. Furthermore I need copy/erase folders and files from Samba.

This is my stack:

version: '2'

services:
  db:
    image: yobasystems/alpine-mariadb:latest
    command: --transaction-isolation=READ-COMMITTED --binlog-format=ROW
    restart: always
    volumes:
      - /srv/dev-disk-by-uuid-2f9dc745-0f9b-413a-b2bf-794d3f087f59/nextcloud/db:/var/lib/mysql
    environment:
      - MYSQL_ROOT_PASSWORD=PASSWORD
      - MYSQL_PASSWORD=PASSWORD
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud

  app:
    image: nextcloud
    restart: always
    ports:
      - 80:80
    links:
      - db
    volumes:
      - /srv/dev-disk-by-uuid-2f9dc745-0f9b-413a-b2bf-794d3f087f59/nextcloud/files:/var/www/html/data
      - /srv/dev-disk-by-uuid-2f9dc745-0f9b-413a-b2bf-794d3f087f59/nextcloud/config:/var/www/html/config
      - /srv/dev-disk-by-uuid-2f9dc745-0f9b-413a-b2bf-794d3f087f59/nextcloud/custom_apps:/var/www/html/custom_apps
      - /srv/dev-disk-by-uuid-2f9dc745-0f9b-413a-b2bf-794d3f087f59/nextcloud/themes:/var/www/html/themes
    environment:
      - MYSQL_PASSWORD=
      - MYSQL_DATABASE=PASSWORD
      - MYSQL_USER=nextcloud
      - MYSQL_HOST=db