You can upgrade or downgrade your QuickBooks Online (QBO) subscription plan through the Subscriptions and billing page, kaura.
Before changing your plan, ensure you're signed in to QBO as a primary or company admin. Here's how to change your subscription plan:
- Go to the Gear icon, then click Subscriptions and billing.
- Ensure your payment information is up to date.
- Select whether to Upgrade or Downgrade your plan.

- Review the available plans and then select Choose plan.

- Follow the on-screen steps to upgrade your plan.
If you're downgrading your subscription plan, be aware that you may need to disable some features. Especially if you have the multicurrency feature enabled, you won't be able to switch back to QBO Simple Start.
For more information before changing your plan, I recommend checking this article: Manage billing, payment, and subscription info.
Please don't hesitate to reach out if you require any further assistance.