DTS or SSIS works manual not scheduled???

By default , when you run an SSIS package manually it assumes your current login . However, when you schedule a package, sql uses the account running MS SQL agent service.

So you can either change the account running the agent service or create a proxy account.
To change the account running the sql agent, please use MS SQL server configuration manager.

Lastly, create a proxy in the SQL studio manager under SQL agent>proxy