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

Set-ClientAccessServer -Identity <Your Server Name> –AutoDiscoverServiceInternalUri https://<Your Server Name>/Autodiscover/Autodiscover.xml

Set-OutlookProvider -Identity EXCH -CertPrincipalName msstd:<Your Server Name FQDN>
 Set-OutlookProvider -Identity EXPR -CertPrincipalName msstd:<Your Server Name FQDN>
 Set-OutlookProvider -Identity WEB -CertPrincipalName msstd:<Your Server Name FQDN>

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

Set-OutlookAnywhere -Identity '<Your Server Netbios Name >\Rpc (Default Web Site)' -SSLOffloading $true -ClientAuthenticationMethod NTLM -IISAuthenticationMethods Basic,NTLM -InternalClientsRequireSsl:$False
 Set-OutlookAnywhere -Identity "<Your Server Netbios Name >\Rpc (Default Web Site)" -InternalHostname <Your Server Name > -ExternalHostName <Your Server Name > -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 <Your Server New Name >
 Get-Mailboxdatabase | Set-Mailboxdatabase -RpcClientAccessServer <Your Server New Name >

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