When we change the parameters in the RAC systems, I always recommend to specify the SID clause clearly, which means you know which or all instances will be modified.
If you ignore it, the result will be dependent on if the instance is started by spfile or not:
If you do not specify this clause, then: If the instance was started up with a pfile (traditional plain-text initialization parameter file), then Oracle Database assumes the SID of the current instance. If the instance was started up with an spfile (server parameter file), then Oracle Database assumes SID = '*'.
As a DBA or SA, when we will run any command, we should try to know the result clearly. This habit will avoid plenty of unexpected results.