It's almost always the campaign's bidding strategy. When a campaign uses automated bidding (Target CPA, Target ROAS, Maximize conversions, Maximize conversion value, or Target impression share), Google ignores bid adjustments for gender, age, income, and parental status. This is a Google rule, not an Ads Editor limitation. The Demographics window shows this warning at the top when it applies.

The adjustment stays saved and applies again if you switch the strategy to Manual CPC or Maximize clicks. If your goal is to stop advertising to an audience, use Exclude on that row: exclusion works with any strategy.

About household income: it's available in Brazil (and in other countries, such as the United States, Mexico, India, Japan, and Australia). The ranges are percentiles within the person's region: top 10%, 11% to 20%, 21% to 30%, 31% to 40%, 41% to 50%, lower 50%, and Unknown (people Google couldn't classify). It works like the other dimensions: exclude, adjust the bid, or return to the default.