I repeat myself quite often. Sometimes I even realize I’ve said the same thing before and copy what I wrote previously instead of typing it out again. Am I a plagiarist? If I plagiarize myself, who is the victim?
As for who the victim is, typically the direct victim would be the funder: if you received a grant to pursue novel research and it turns out you were just rehashing prior work, then you have stolen funding. Similarly, if you are under the employ of a university, then you have stolen funds by reproducing old research and passing it off as new...instead of actually producing new research. These are of course only the monetary victims, the broader victims are those robbed of scholarly advancement by having your job title filled by someone who recycles material versus advancing the field.
I see no reason to change terms and structure in scientific publications so as not to plagiarize myself.
There generally is no reason to change terms and the like. The solution is simply to cite one's prior work when quoting from it - the lack of the latter (citing that a given text is one's prior work) is what constitutes self-plagiarism, not the mere reuse of terminology.