Adding a serial number as customer ID

Hi,

I have created few customers without setting a serial number for customer .

Now If I set a serial number and then create a customer no serial number is assigned to the newly created customer.

Does it mean I can only assign serial number at the beginning before creating any records?

Please suggest.

Thanks.

By Serial No, you mean naming series? You can reset your series anytime.

https://manual.erpnext.com/contents/setting-up/settings/naming-series