upgrade from standard to enterprise on a cluster.

SQL Server 2008 R2 Standard
Windows Server 2012 R2 Standard.
Two node Active/Passive Clustered, lets say NodeA is active and NodeB is passive.

Need to upgrade the edition only from standard to enterprise.

Want to understand if we need to apply the upgrade manually on both the nodes one by one
or Only we apply the upgrade only on the passive node and it will get applied to the active node by itself once we failover to the passive node. Lets say we first run the upgrade from the passive node NodeB and after the setup completes, we manually fail-over from NodeA to NodeB. Once we fail-over, SQL Server will automatically apply the upgrade on the NodeA which is passive now. Any step by step documentation will be helpful.
**** All the links I checked till now look ambiguous to me *****

Thankyou.