Jmeter: How to map specific variable values from CSV file to specific thread-groups in a test plan

Threads and thread groups are different things. When you choose "All Threads" in "Sharing mode", it just means that all threads in the same thread group will share CSV. Thread groups are always independent.

You have 2 simple options:

1. Use one thread group and control what users are doing with controllers. For example Throughput Controller can allow you to control how many threads perform this or other script scenario within the same thread group.

2. Split your CSV so, that each thread group has its own CSV.

And many more complicated options, for example:

3. Use __CSVRead or __StringFromFile function, which allows to read one line. That way you can assign each thread group a range of lines to read, rather than reading the entire file.

4. If your usernames and passwords are predictable (e.g. user1, user2, etc), you could use a counter and a range for each thread group.