North VS South (and Central)
I'm trying to learn Vietnamese, but most questions (if not all), are read in the North dialect. My family is Southern Vietnamese, so they are lost when I attempt to mimic any of the speech. There should be an option to change everything to the Southern or Central dialect!
If you want to know about the Southern Vietnamese pronounciation of the words, you can simply look them up in Wiktionary (https://en.m.wiktionary.org/wiki/Wiktionary:Main_Page). The articles about Vietnamese words usually contain information about the pronounciation in the accents of Hanoi, Hue and Saigon, representing their pronounciation in IPA.
Edit: It might be annoying to look up every word's pronounciation in Wiktionary, but after some time you can make up the Southern Vietnamese pronounciation automatically.
Unfortunately this option does not exist and probably will not. Duolingo tries to teach the most dialect-neutral version of every language. This means that the Spanish taught in the Spanish course will be understood by people across the world, Portuguese will be understood in South America and Europe, and Vietnamese will be understood all around Vietnamese. Although Duolingo strives to do this, it is impossible to be completely dialect-neutral unless you teach super formal vocabulary (super formal vocabulary doesn't really help in everyday conversations). In the Vietnamese course, the vocabulary is meant to be neutral, but Northern Vietnamese audio is used. Unfortunately, this cannot be changed. However, you said your family is South Vietnamese, so you can have them guide you through learning Southern Vietnamese pronunciation and even Southern vocabulary.
I think this is an extra tough situation for Vietnamese. North/South Vietnamese seem to be two separate languages that have just recently began their divergence.
These "dialects" aren't all that mutually intelligible without a lot of exposure to the other. My Vietnamese friends who were raised in the US on one dialect, generally regarded by their raised-in-Vietnam friends to have no accent and to speak Vietnamese fluently, absolutely can not understand the other dialect. I think it's similar to the situation of Swedish, Norwegian, and Danish.
As they say, a language is a dialect with an army and navy. If the Vietnam civil war had lead to a split between the North and South, it's very well possible in 100-200 years, possibly sooner!, they'd be regarded as two separate languages and would get two separate courses on Duolingo (eventually).
Or another possible interesting route: since the nation is now united and the Hanoi region dialect has been deemed the standard of the country (with a couple exceptions ), maybe they'll push toward a more standardized language. However, with the large Southern population outside of Vietnam that may never be a complete codification. Hopefully we end up with a sensible pronunciation of "Rượu"
It's honestly not so stark a difference if you give it time. I grew up befriending people from both (and other) regions of Vietnam. It becomes a non-issue with a bit of exposure. Happy learning! :-)