Some Invoicing information is set at the Company level. This means that any time you create a new Account, your default settings will apply to the new Account until these settings are changed. To view and edit these settings, go to Settings > Company Information and select the "Accounting" tab:
NOTE: if you cannot see the Company Information selection on the Settings list, your user rights may be preventing this.
Default AR Account will correspond to the AR Account found on the Invoice under Show Advanced Options:
Invoice Standard Terms determines how soon the Invoice status will change to "Past Due". If "Due on receipt" is selected, Invoices will show as "Past Due" as soon as they are generated.
Default When to Invoice determines when an Account's Invoices are generated. If this is set to "Daily" then Invoices will be generated as soon as Jobs are completed. If it is set to "Monthly" then all Jobs that are completed for the Account in the month will appear on the same Invoice. Custom Billing Day will only apply if the Invoice frequency is set to the custom option.
The last Invoicing field at the Company level is Default Send Invoice By. This will determine whether Invoices need to be printed, emailed, or both.
These settings are only the Company defaults. They can be customized at the Account level.