WHy expense is adjusted when payment is adjusted .Ideally it should be adjusted with supplier and should effect expense ledger

Welcome to the Community, Zubeda.
 
In QuickBooks Online (QBO), whether an expense is adjusted when a payment is adjusted depends on which workflow you used. QBO operates on a double-entry accounting system, but the accounts affected differ based on the transaction type.
 
If you used the Bill and Bill Payment workflow, the bill records the expense and creates a supplier balance in Accounts Payable (AP). The bill payment reduces AP and your bank account, but does not adjust the expense. If adjusting payment alters the expense, it may indicate an unapplied payment or processing issue.
 
However, if you used the Expense or Check feature to pay a vendor directly (without creating a bill), the payment immediately records the expense and bank deduction. Changing the payment in this case updates the expense since no AP is involved.
 
You can review the transactional journal, which provides a clear breakdown of how each account is affected by the changes made to payments or expenses.
 
Here's how to check the Transaction journal:
 

1. Go to the My apps in the left navigation, and select Bill.
2. Open the Bill you want to view.
3. At the bottom, click the More option.
4. Choose the Transaction journal.
    

If you're unsure about your situation, consult an accountant to ensure your books are accurate. They can clarify how adjustments affect your records and guide you on best practices in QuickBooks Online.

Feel free to return here anytime you need assistance.