@Pawel I am having the same issue. Tried removing serverless and reinstalling but same issue (specifying an an aws profile, but deploying to my main aws account)
I tried absolutely everything to persuade serverless to use a profile from my aws-cli credentials. Absolutely nothing worked at all.
I had linked my web serverless dashboard to my serverless CLI, and that created a default profile for deployment. It turned out that the serverless CLI was using that default profile from the web dashboard for all my stage deployments, despite specifying a different profile everywhere else. The only way I found to override it was to establish a second profile in the web dashboard, link it with the right AWS account in the web dashboard, and explicitly set that profile to be used for the right stage in the web dashboard.
–aws-profile in the serverless CLI, AWS_PROFILE= in the serverless CLI, and profile: in serverless.yml, had absolutely no effect. This is with the latest code in 2020-03.