You cannot change the settings for an already existing search agent. To change your criteria, you have to create a new search and activate the search agent again for the search that you have just made.
To remove your old search agents, use https://bostadsportal.se/en/agents/ and simply remove them.
And if you want to create a new one, you simply make a new search, adjust the results with a filter if needed and "Turn on" the function.