You have likely already integrated with Xero, but for some reason, you may not see an option to select in the "Xero payment account" . The reason for this is likely because you do not have a code inserted in your bank account.

To create this code, go back to your Xero account and click "Accounting" then select "Bank accounts".

You should see a list of all your bank accounts, click on the name of the account in blue.

You should be led to "Edit Account Details". Go to the "Code" section and add any unique number which will represent this particular account, do this for any accounts you may have.

Do ensure that your Xero Payment account is a Bank account type as below:

Click the green button "Save" at the bottom.

Go back to Semble, refresh your page and you should now be able to select the accounts for the payment account.