I am confused about the different solidity versions in each course, 0.4 and 0.5, whereas the current version is 0.8. The question is should I search to find the course that works with the latest solidity version 0.8? And is Solidity 0.4 or 0.5 outdated? I can see something about the solidity version modifier, is that practical?
There is no simple answer to this question, but I will give it a try.
It would be of course best if you can find a course that is using the version 0.8 of Solidity. That way, you can learn all the latest Solidity features that were introduced in the past couple of years. However, fact that the course us using version 0.8 should not be the only criteria. For example, it is also important that the course has good approach in teaching you the concepts of smart contracts and how is that realized on the Ethereum platform. I personally have learned Ethereum platform and Solidity using a course which uses outdated Solidity version. But the course itself was good, and has given me a good foundation. It was easy for me to then pick up the differences that were introduced in the later versions. However, note that I am an software engineer with over 10 years of experience, so that helps a lot.
With all that said, my suggestion would be the following. If you are an experienced developer, just go with any course that has good reviews, you can figure out the differences between the version without much issues. If you are however new to the world of software development, try finding a course that uses some more recent version, as you might struggle with some of the differences.