Exchange Self Sign Certificate Expired ( Microsoft Exchange and Microsoft Exchange Server Auth Certificate)

Hi Team,

I have exchange 2013 setup and I noticed that "Microsoft Exchange Server Auth Certificate" is already expired and "Microsoft Exchange" self signed certificate is yet to expire next week. 

as per the below link I thought self signed certificates in exchange will renew automatically. can you please confirm me whether I need to renew it manually or it will renew automatically.

https://www.experts-exchange.com/questions/29074194/Certificate-Microsoft-Exchange-Server-Auth-certificate-expiry-renewal-MS-Exchange-2013.html

If I suppose to renew manually, please help me with the steps for both certificate renewal. (Auth Certificate and Microsoft Exchange) auth certificate is already expired and another one is about to expire next week.

Thanks

Vikram