You can specify which specific customer should go to Crik-IT. 

Just log into Crik-IT as a Crik-IT administrator and click the Tools tab, then click Crik-IT / QuickBooks Config Menu 

Then, choose Other Configuration.

At the top section of the Other Configuration page is Customer Configuration and within that box you will find Which of your customer should show up in Crik-IT options.

Want to have only some of your customers go to Crik-IT?  You have two choices:

1) If you want most of your customers in QuickBooks to go to Crik-IT, choose the "Only customers without "DoNotSendToCrik-IT" anywhere in the Customer Notes field in QuickBooks" option.  Then, in QuickBooks, for each customer that you do not want to have show in Crik-IT, put "DoNotSendToCrik-IT" (without the quotes) in the customer notes field.  Make sure you save your settings.

Then, here's how you should set up a customer in QuickBooks Online that should NOT be sent to Crik-IT.

2) If you want most of your customers in QuickBooks to NOT go to Crik-IT, choose the "Only customers with "DoSendToCrik-IT" anywhere in the Customer Notes field in QuickBooks" option.  Then, in QuickBooks , for each customer that you do want to have show in Crik-IT, put "DoSendToCrik-IT" (without the quotes) in the customer notes field.  Make sure you save your settings.

Then, here's how you should set up a customer in QuickBooks Online that SHOULD be sent to Crik-IT.

If you have already done your initial data sync, after changing any of these options, from the Crik-IT /QuickBooks Config Menu, choose "Sync Your Data"

Then select "Let me choose what to sync", then "Sync Customer Data".

When the sync finishes, return to the Configuration Menu, then click "Return to Crik-IT" link at the top of the configuration menu page.