Does custamize doctype reset after update?

If I make custome field in purchase invoice or order or sales invoice or order or make some changes
Will it be reset after update of frappe and erpnext ?
How I could make permanent changes in purchase invoice or other doctype? To avoid reset

Custom fields added via Customize Form will not be replaced or removed after updating.

Thanks for your reply I mean if I make changes in invoice in erpnext will it be remain after update?
If I make invoice in custom app how I can use it by default in erpnext?
And you said added custom field via custmize form will not change how I can make it?

Please Read

Thank you so much I will check it