One of the following stores RNA :
1 . Nucleolus
2 . Nucleus
3 . Mitochondria
4 . Plastids
RNA can be found anywhere in the cell including the nucleus.
Note that RNA are made in the nucleus through the process called transcription, The first made RNA is called a pre-RNA. The pre-RNA is processed by an enzyme call spliceosome. Then, the mature RNA stays in the cytoplasm to accomplish multiple functions. Also note that, you can find many types of RNA in the cytoplasm of cells such as mRNA, tRNA .....