How to change exchange internals/externals URL’s

The best way to change exchange URL’s is with Exchange Powershell, here is all the commands you need :

Set-WebServicesVirtualDirectory -Identity "\EWS (Default Web Site)" -InternalUrl https:///EWS/Exchange.asmx -BasicAuthentication:$true
 Set-WebServicesVirtualDirectory -Identity "\EWS (Default Web Site)" -ExternalUrl https:///EWS/Exchange.asmx -BasicAuthentication:$true

Set-ClientAccessServer -Identity  –AutoDiscoverServiceInternalUri https:///Autodiscover/Autodiscover.xml

Set-OutlookProvider -Identity EXCH -CertPrincipalName msstd:
 Set-OutlookProvider -Identity EXPR -CertPrincipalName msstd:
 Set-OutlookProvider -Identity WEB -CertPrincipalName msstd:

Set-ActiveSyncVirtualDirectory -Identity "\Microsoft-Server-ActiveSync (Default Web Site)" -ActiveSyncServer "https:///Microsoft-Server-ActiveSync" -InternalUrl "https:///Microsoft-Server-ActiveSync" -ExternalUrl "https:///Microsoft-Server-ActiveSync"
 Set-EcpVirtualDirectory -Identity "\ecp (Default Web Site)" -InternalUrl "https:///ecp" -ExternalUrl "https:///ecp"
 Set-OabVirtualDirectory -Identity "\OAB (Default Web Site)" -InternalUrl "https:///OAB" -ExternalUrl "https:///OAB" -RequireSSL $true
 Set-OwaVirtualDirectory -Identity "\owa (Default Web Site)" -InternalUrl "https:///owa" -ExternalUrl "https:///owa"
 Set-PowerShellVirtualDirectory -Identity "\PowerShell (Default Web Site)" -InternalUrl "https:///powershell" -ExternalUrl "https:///powershell"

Set-OutlookAnywhere -Identity '\Rpc (Default Web Site)' -SSLOffloading $true -ClientAuthenticationMethod NTLM -IISAuthenticationMethods Basic,NTLM -InternalClientsRequireSsl:$False
 Set-OutlookAnywhere -Identity "\Rpc (Default Web Site)" -InternalHostname  -ExternalHostName  -InternalClientAuthenticationMethod ntlm -InternalClientsRequireSsl:$True -ExternalClientAuthenticationMethod Basic -ExternalClientsRequireSsl:$True

To change The server name to specific mailbox database you should use this to get the name of the database and the RPCClientAccessServer:

Get-MailboxDatabase | fl RpcClientAccessserver
 then you can issue those command to change the server name
 Set-MailboxDatabase -identity "Mailbox Database name" -RpcClientAccessserver 
 Get-Mailboxdatabase | Set-Mailboxdatabase -RpcClientAccessServer 

alternative you can use digicert tool (Download from here) :DigiCertINTool

Or From Digicert : https://www.digicert.com/internal-domain-name-tool.htm

You can also use Microsoft script to that : https://social.technet.microsoft.com/wiki/contents/articles/5163.managing-exchange-2010-externalinternal-url-s-via-powershell.aspx

Good Luck