I need a better word for this than "snoutband"

According to dictionary.com:

A snoutband is someone who always interrupts a conversation to correct or contradict the person speaking. Every social group has a snoutband, who thinks they know everything. They probably don't know the meaning of this word, though. At least, not yet.

But nobody uses this word! There has to be a more formal, more appropriate synonym.

I would describe such a person as nitpicky and pedantic.

nitpicky

1. Finicky; overly critical; concerned with insignificant details.

pedantic (comparative more pedantic, superlative most pedantic)

1. Like a pedant, overly concerned with formal rules and trivial points of learning.
2. Being showy of one’s knowledge, often in a boring manner.
3. Being finicky or fastidious, especially with language.

You could use nominal forms and call such a person a nitpicky pedant or pedantic nitpicker. You could forgo one of the words in description, but people should understand what is meant.

who thinks they know everything

In British usage we have know-it-all or Know-all

Buttinsky

: a person given to butting in : a troublesome meddler

there's always some buttinsky who has to tell you there's a better way to do whatever you're doing

"Buttinsky." Merriam-Webster.com. Merriam-Webster, n.d. Web. 3 May 2017.