I did this on mobile, but I would do it all twice to mute it on both mobile on desktop. It's one of those UX things that's gonna make it hard to get new users onboard Lemmy, unless the UX can be improved to allow muting words directly within Lemmy and storing the list by Lemmy account.
I wish at the very least, Voyager allowed one to export the muted words list to a file and import the file, which could mitigate some of the hassle. On Mastodon, I have like 75 muted words covering news and politics, so muting them all is just painstakingly time consuming if I have to do it twice, and then updating the list twice as I come up with new words that need muting/blocking.