How to change invoice numbers to sequ. and regenerate old ones

[hastla]

Hi,

 

I wanted to ask if there is a possibility to set up "sequential paid invoices" in past now and change the existing ones from 1 to xyz. Would this be possible without any problems in the ordering system? It would be nice to get this fixed, as it was a missing thing, when we set up WHMCS.

 

I also saw "Only change this if you need to regenerate an invoice number" - so I think maybe there is a chance to get this fixed in past - regenerating invoice numbers would be exactly the thing what we need. So how can we do this? Thank you for your help!