It is only on-topic where the problem is with or in using the desktop PC based client.
If your problem is with the Android application then there would be Android Enthusiasts or for Apple devices you could ask at Ask Different. Otherwise for the web chat (in your browser) version it could be asked at Web Applications.
If your problem is in setting up an ...
You can edit your watch tags in the side bar of the main site where there is an "edit" button on your watched tags.
Clicking "edit" will change the tags to add an "x" to remove them or add a box where you can add more tags: