English must be altered to suit different purpose and different audiences. yes or no?

Yes, because some languages don't use a lot of the words

Hi!

When we're going to be using English to communicate a message, we must alter it based on the purpose, and the audience intended.

For example, would things really work out if we were talking to an audience of children using the language of an adult? Well... They most likely won't understand what we're trying to say.

The purpose also matters. If your purpose is to deliver an informational presentation, then perhaps it won't be the best idea to pitch it in the form of poetry. 

We must shape and change our language based on what we're communicating, and who we're communicating it to. 

Hopefully, this helps! =)