If you have created additional FTP accounts and experience any login problems, please double check if your username is correct. For example, if your username is u334914894 and you created new FTP account "alex", your FTP username will NOT be alex, it will be "u334914894.alex" instead.
To make a desired directory/file writable, simply change file permissions to 775, if you want everyone to be able to write into the directory, set the permissions to 777. It can be done via file manager from the cPanel or via FTP client. Right click on the file and select "Permissions".
UltaHost does not support anonymous FTP connections for security and performance purposes.