Hi Yukari,
Thank you for your post and welcome to the MYOB Community Forum. I hope you find plenty of useful information.
Usually, to record a partial payment you need to:
- Open the Pay Bills/Receive Payment screen (depending on whether you are recording for a Purchase or a Sale respectively)
- Choose a Supplier/Customer.
- Fill in the Amount Paid/Amount Received at the top of the payment.
- Fill in the date.
- Click into the invoice you want to apply the amount to so that it has just the partial amount written there (not the full amount)
- Click on the Date or Memo line. You'll see the Out of Balance amount is $0.
Please see the attached screenshot for further information.

You may also have a look at this help article receiving payments that has detailed information and instructions to assist with this.
If you need further help, don't hesitate to start a new post and we'll be happy to assist.
Otherwise, if my response has answered your enquiry, please click "Accept as Solution" to assist other users find this information.
Cheers,
Shella