[Jimbee (OP)]

Like I said before on this board, using the singular form of you (which is thee and thou in English) fell out of use a couple hundred years ago. That's called tutoyer, after the French singular forms of you "tu" and "toi". It is more familiar and some people think it is disrespectful. So by George Washington's time, almost no one ever used it. (It is still modern English though. Because we still use it. In poetry, religion, quoting Shakespeare, etc. Like in the 1980 Diana Ross song "Upside Down":

"'Round and 'round, you're turning me
I say to thee, respectfully.")

But by Washington's time, we switched to the plural of the second person you, which is you and ye. So whatever happened to ye? We don't seem to use it anymore.

Also, is there some advantage to having one form of the second person pronoun? For example our definite article, the, is only one form. And people say that is a good thing. Artificial languages usually copy it. Because, among other things, you can always find it in a sentence. Because it is only spelled one way.

So what happened to ye?

[Bored chemist]

Like I said before on this board, using the singular form of you (which is thee and thou in English) fell out of use a couple hundred years ago.

A lot of folk in the North of England don't agree with that assessment; and they sometimes use  "ye" too.

[Petrochemicals]

It got put in gaol.