Lock certain 'Payment'

Is it possible to lock a certain expense encoded in Payments tab? We have multiple users and there are expenses which are confidential to other like Payroll. Can a certain user lock 1 encoded payment?

No. User permissions do not apply to individual transactions.

Do you have any suggestions to keep others as confidential or not viewable to them without losing the access to Payment?

Not unless the payments come from separate bank accounts. You can restrict access by bank account, too.