As you can guess from the error....one of your queries is returning more than a single value. But I won't be able to help you much just by looking at the code.....so you could either provide DDL and some sample data which would depict your problem and then perhaps we could correct the code for you.

Otherwise, you can just replace the "=" signs before the sub queries with "IN". But, that is if your data permits that as it could create results that you are not trying to do and might update more rows than actually you intend to update.