A lot of you guys might be confused about what's going on with Venezuela. Anyway, the Sovereign experienced hyperinflation so the "Digital" was introduced to take off 6 zeros; 1,000,000 Sovereigns is equal to one Digital. This isn't a replacement though, Sovereigns are still accepted at a ratio of 1 mil to 1.
It's not actually digital, that's just its name. Physical "Digital" notes are still issued. Since the Venezuelans don't trust their currency either, a lot of transactions are done in USD.
As for the others; El Salvador is just trying to be trendy, and Panama has always been de-facto dollarised. Their currency is pegged at par with USD (1-1 ratio), and no notes are issued.
It's not actually digital, that's just its name. Physical "Digital" notes are still issued. Since the Venezuelans don't trust their currency either, a lot of transactions are done in USD.
As for the others; El Salvador is just trying to be trendy, and Panama has always been de-facto dollarised. Their currency is pegged at par with USD (1-1 ratio), and no notes are issued.