Allow me to provide some information about how accounts are affected by debits and credits.
QuickBooks Online (QBO) uses double-entry accounting, which means each transaction involves a debit and a credit applied to one or more accounts.
The entries of debits and credits are handled by QBO for most transactions. You might want to check out this article to understand the basic functions behind transactions and what to expect when entering them: How accounts are affected by debits and credits.
On the other hand, the possible reason why there's no callback option is that the support hours for live agents aren't available yet. Please check this article for the different types of support we offer at Intuit and its availability: Support hours and types.