“my email ID has changed” vs “my emil ID is/has been changed”

Question

I want to ask one thing. Sometimes we hear people say

my email ID has changed.

As per my understanding present perfect tenses need a subject which is missing above.
I find these sentences little bit weird because I think we should have subject in using present perfect if it is not passive one.

I think we should say

1. my email ID is changed
   or
2. my email ID has been changed.

Please help me out to use present perfect effectively, the present perfect tense make me confuse.

Answer 1

This isn't a matter of the perfect construction but of two different senses of the verb.

Change is what is sometimes called a “labile” verb†. Labile verbs are used in both transitive/agentive and intransitive/stative senses: for instance, we say both

• Water is boiling on the stove (intransitive/stative—we’re describing the state of the water)
• I’ll boil water for tea (transitive/agentive—we’re describing my action)

Change works the same way: we say both

• Her hairstyle has changed and
• She has changed her hairstyle.

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† _{Other terms for this phenomenon are “middle voice” and “mediopassive voice”—I used them myself until I was introduced to “labile”—but these have somewhat different senses in their core uses, and should probably be avoided. See this question.}