Io sto imparando   (sto with no accent)
tu stai imparando  
egli sta imparando (sta with no accent)
noi stiamo imparando 
voi state imparando 
essi stanno imparando

It does not change with the subject and it does not get the plural like you suggested.

Just remember that the construction of the present continuous it subject + verb to be + verb(ing). So the ing form of the verb imparare is imparando. Imparandi does not exist.

I have to correct something regarding my previous comment

The italian equivalente of this <questo> with the elision <'sto> is used only in talking but is not accepted in written.

Elision is accepted in written form only in certain cases and for a very limited number of words

Some examples

<po'> instead of <poco> (few)

<be'> instead of <bene> (well)

<ca'> instead of <casa> (house)

etc.etc

just a detail.

sto' <- in italian the character ' (apice) is used for elision, example:

questo (this) can also be written o said  'sto (this, the same as questo)

not all words can be truncated with elision, another example is the word "poco" (few) 

po' <- this is not an accent but an elision, it means that the word "poco" has been truncated