I've made that change for you. Please note that it may take up to 2 hours for your new domain to fully work. If after a full 2 hours it doesn't work on your side, please make sure you clear your web browser cache: https://wiki.helionet.org/Clear_Your_Cache
Please note there is a risk of data loss when main domains are changed, so I made a full backup for you before I made the changes, in case you need any files from the old domain. You can download the backup here: https://heliohost.org/backup
If you're not sure how to extract the backup files, please follow our how-to guide here: https://wiki.helionet.org/Account_Backups