How Account Record Type Is Determined During Lead Conversion

When Multiple Business Account Record Types Exist

If the lead is converting to a business account and the user has more than one business record type available — say Record Type 1 and Record Type 2 — Salesforce defaults to the business record type marked as Default under the "Default Record Type" section in Profile > Record Type Settings.

When the Default Record Type Is a Person Account

If the default in Record Type Settings is a person account record type, the business account record type used during conversion is instead based on created date. In this same scenario, when converting a lead to a person account, the record type is picked based on the overall default.

Salesforce does not use the defaults configured under the "Business Account and Person Account Default Record Types" section for this. Lead convert picks up the overall default, not the sub-default.

Related Enhancement Request

This behavior is tracked as a product enhancement request. See the idea below and add your vote if you'd like this changed: Standard and Person Account Record Type Defaults in Lead Conversion.