"Remain where you are!"
Translation:Rimanete dove siete!
They are interchangeable, but it is mainly a regional difference. In the south of Italy, you will find that they use "stare" for location. They might say something "dove stai?" instead of "dove sei", or "ci sta" instead of "c'è". Why? It's because the south is more influenced by Spanish, and for those not taking Spanish, it also has two verbs for "to be", ser and estar, which correspond to the Italian essere and stare. In Spanish, you must use estar (stare) for location. Having learned Spanish first, I tend to want to use stare, but DL uses essere, and I've just gotten used to it.
There are three options:
Rimani dove sei! [informal singular you, tu]
Rimanete dove siete! [informal plural you, voi]
Rimanga dov'è! [formal singular you, Lei]
Note that both verbs in the sentence--the imperative of rimanere and the present tense of essere--need to agree with whichever (implied) subject is used (tu, voi, or Lei).
Because this is the formal (polite) form for "rimanere" (the informal is "rimani"). So for that you would need to use the 3rd person. Ex. "Rimanga dove (Lei) è". remain where you (singular) are.
Note that this also applies to the possessive pronoun. Ex. "prenda (formal) la Sua chiave" take your key".