My iPhone 5 currently has iOS 10.3.3 and when I look at updates says it is up to date. How do I update to 10.3.4?

Only model 5 can support iOS 10.3.4. (not 5c, not 5s).

See this article:--> Update your iPhone or iPad software to avoid issues with location - Apple Support

Regards

Giulio

Which iPhone do you have? 5? 5c? 5s? It's only the iPhone 5 that is affected, NOT the 5c or 5s.

If you have a 5s, i can recommend updating to the latest, 12.4.3.

The 5s is fine. You do not need the update.

Glad it helped :-)

Giulio