For new words, is there an appointed person who creates/decides on 'official' signs for ASL?

It varies by community. My sister’s husband was a deaf missionary in Ghana for a couple years. When he was there, he pretty much was the one that standardized the signs between the various communities.

Each village had it’s own unique sign language and he took bits from each to create a language that could be understood by all. It helped that he was only there to set up the mission, and would be leaving. He was trusted to mediate so that no group felt slighted.

Edit – I should add that he found the ASL signs used in Omaha, were different from those used in St. Louis, Rochester, or southern Wisconsin. So even in the US the signs are not always quite the same.

@WestRiverrat Thank you for that informative answer. So it seems that ASL varies depending on location, kind of like spoken languages. In Maine, I call it an oven mitt, my aunt in Georgia calls it a hot hand. :)

There are standard ASL signs that are used nation wide, over just as with English or any other language for that matter, like WestRiverrat suggested, there are many variations among Deaf communites, and different “slang” is used in each- among friends, states, cities etc. when people of the Deaf community get together and one does not understand a sign, they just explain what they’re saying in a different way until both people are on the same page, and then retain that sign from that poin on, and can now use either interchangably

My whole family is deaf and I think it’s basically like what @boxer3 and @WestRiverrat said.
It varies from community to community, for example: I went to Kansas to visit the Deaf institution there and the signs there were slightly different, I went to Fremont school in California and their way of signing were different.
Not only by the signing but by the way they express themselves, in my opinion the people from Fremont were more loud and bubbly than the people I met in Kansas.
So like I said, it really varies from community to community.
:]

@Everyone, thank you all for the great answers.

@pitchtheview I am hearing. How can signing be “loud” as you wrote? Just curious.

@kelly I am also hearing. If you spend any amount of time with someone that signs, you will quickly learn how to judge the tone of a conversation. You won’t even have to know how to sign to judge the “loudness”.

@kelly
Hmmm… It’s hard to explain but like, they use a lot of facial expressions and their hands fly everywhere. Like @WestRiverrat said, if you spend a lot of time with people who sign, you can tell the difference.

Thanks, I learned something new today.