You can use a Swiss Schengen visa to travel to Austria/Greece but you have to pay attention to a few other things than its period of validity:
The visa should be valid (it's your case as you said it's valid for one year) but also allow multiple entries and sufficient length of stay (both are also mentioned on the sticker). For example, if your visa is a single entry visa, you cannot fly to Switzerland, leave the Schengen area and then reenter in Vienna. And multiple entry visas are generally intended to offer the holder more flexibility so it's very important to check whether yours is indeed a multiple entry visas.
If you show up somewhere completely unexpected, you might be asked why you have a visa from Switzerland and challenged to prove you meet all the other conditions for entry. That's why it's always advisable to first complete the trip you described on your application and then see about doing another trip. Having already entered the Schengen area and left once without incident also increases your credibility.