Hello Asfaqur Rahman,

I would like to inform you that in previous versions of Odoo, there was no option to set an analytic account directly on a task. Instead, the analytic account was assigned at the project level.

However, in Odoo version 18, there has been a change in how the analytic account is managed within projects. The option to configure an analytic account has been moved to a newly introduced tab within the project’s form view.

For further reference, please check the attached screenshot.

Hope this information will help you.

Thank you. Have a nice day!