Song

Don't Stop Believin' was first sung on Glee in the pilot episode with Rachel (Lea Michele) and Finn (Cory Monteith) singing the lead backed by Kurt, Artie, Tina & Mercedes.
Watch this version below.

It was next done by New Directions in the season 1 finale 'Journey' also known as 'Journey to Regionals' this time solos were sung by Rachel, Finn, Kurt, Artie, Puck, Mercedes & Santana
Watch/Listen to this version below

The next time the song is performed is in the 19th episode of season 4. It is sung by Rachel (Lea Michele) for her Funny Girl audition as she imagines Artie, Finn, Kurt, Mercedes, and Tina singing back-up. This is also the final episode & performance done by Cory Monteith before his sudden & tragic death on July 13, 2013
Watch this version below

The final time it's performed is in the 13th episode of season 5 as part of the second half of the 100th episode tribute. This time it is peformed by all of New Directions (old and new) and joined by Will Schuester as they all say goodbye to the McKinley High Glee Club for the last time.
Watch/Listen to this version below