Lower site TTL

So my TTL is currently 4 hours, and I was curious if there was a way to lower it to lets say, 30 seconds?

Without knowing who your domain registrar is, it is almost impossible to say.

In general though if your registrar allows you to manipulate DNS records there is usually a setting to adjust TTL. How low you can go on the number is often constrained by the registrar.

When updating records and verifying they have been added correctly my target TTL is 300 seconds (5 minutes). This number is an old school number from the early days of DNS.

Once things have been verified, then you up the number to 86400 seconds (24 hours).

DNS is poll and cache system and depends on folks not pushing it by using really low numbers over long periods of time.