I had this problem with a fork from some online course. I cloned my fork and ran into a permissions error. I couldn't understand why it was insisting I was my user from my other company. But as the previous commenter mentioned I had the Clone git repositories using ssh setting checked and I had forgotten to add an ssh key to my new account. So I did and then still couldn't push because I got THIS error. The way I solved it was to push using the Github Desktop client.
Takeaways:
- When you open a new GitHub account make sure to add an ssh key to it
- Use different ssh keys for different accounts
- In general I run into some GitHub issue on IntelliJ at least once or twice for every project. Make sure you have a copy of GitHub desktop and load your projects into it. It can and will help you with lots of problems you may run into with Intellij - not just this one. It's actually a really nice GUI client and free!
- It probably makes sense to do what @yabin suggests and use the native client on a Mac