I submitted a paper to Journal of comparative physiology-B. After major revision, two reviewers gave me minor revision (only change one word) and the editor was pleased to consider publication. After re-submission, the status changed from "under review" to "decision in process". However, the status was then back to "under review". What does it mean?
The question presupposes that the behavior of such an editorial system has a meaning. Granting that presupposition, my first guess is that the editor got the reviewers' reports and was about to make a decision ("decision in process") but then noticed that something was unclear in one of the reports and asked the reviewer for a clearer report ("under review").
From the perspective of a reviewer, it's just a button you press. Sometimes you accidentally press one button, even when you meant another. In your situation, the change it status might now mean anything and it's still under review.