There are two ways to configure this SNTP server selection.
(The switch only supports SNTP V1 & V2 and not NTP. )
Assuming your Switch can route to the internet, and has a DNS server configured.
1. CLI configuration mode -
sntp server 2.pool.ntp.org version 2
sntp server pool.ntp.org
2. GUI - System / System summary --- Select Time Server hyperlink in the first System Information window. After making changes, Apply(Bottom) and Save( at the top).