What is your nostr clients? If it is Amethyst you can set it with something like this

"Down arrow" icon meaning is to set relay as "Read" relay while "Up arrow" is to set as "Write". You can set both active or just one arrow icon.

Example:

nos.lol - write and read

nostr.wine - read

wot.utxo.one - write and read

nfrelay.app - read

relay.damus.io write

and etc.