You can use an input filter to consider only a single payout (for the payout you want to sync). For this, please use the below steps:
First, get the Payout Id from Shopify. Access the list of Payouts using URL: https://.myshopify.com/admin/payments/payouts and open specific payout to get the ID in the URL. Then,
1. Open the Shopify – NetSuite Integration App and select ‘Payout’ section. Click on the flow ‘Shopify Payout to NetSuite Payout Custom Record’.
2. Click on the ‘+’ icon under the bubble ‘Post Payout Custom Records to NetSuite’ and then open the input filter using the ‘filter’ option (see screenshot below and note this is shown once you click on + icon)
3. Select the payout id that you want to sync and save the page as shown below.
4. Run the flow ‘Shopify Payout to NetSuite Payout Custom Record’ to sync the payout.
Note: Please note that these entire changes have to be revoked when you want to run the flow again to sync more payouts.