Publishing a conference version of a journal paper at the same time ? (copyright issues)
The problem is that you have painted yourself into a corner.

You have made a very serious mistake by submitting simultaneously to a conference (with formal proceedings) and a journal. Most likely both the conference and the journal have explicit rules forbidding this, and in any case any kind of simultaneous submission is highly unethical: you are abusing the peer-review system.

No matter what you do, someone will be upset.

If you are a student, perhaps the best approach is to play stupid. Contact the conference organisers, apologise sincerely, explain that you were not aware that simultaneous submissions are not permitted, explain that you are just a student, apologise again, and withdraw the conference paper.

The conference organisers will be upset. But maybe this is much better in the long run than proceeding with the publication of both versions, in which case you will make your mistake public and anyone is able to see it (conference submission &amp; acceptance dates are public information, and journals typically publish the submission &amp; acceptance dates of the articles).