"changing subject" is a valid phrase and can be used in written English.
You can use it in situations when you want to switch topics after discussing something else. For example: "We were talking about the weather, but let's change subject - did you hear the news?".
Changing subject, the pair ended on a political note: "Today it has been announced that Margaret Aspinall and Trevor Hicks have been made CBEs in the New Year honours for their services to bereaved Hillsborough families.
Changing subject area is a challenge but is mostly about reapplying skills you already have and remembering how to learn again.
Human evolution is a rapidly changing subject of great public appeal, as any survey of international press, television, and radio will reveal.
Degrees that focus on mathematical and computation science are crucial to prepare new students and future scholars for the changing subject matter in the field as research is advancing and new areas of focus are unraveling every day as well as preparing criminal justice practitioners in their efforts to effectively confront the emerging cyber aspects of crime.
Different Hits number and different class of selected entries obtained by changing subject sequence datasets through "Limits by Entrez query" function.
He trailed off, and a reporter tried changing subjects: "Back to Lester".
Magisterially changing subjects, Mr. McCourt then toasted what he called "the fake Scottish accent" of the proprietor, the eponymous Mr. McIndoe.
"If you're considering changing subjects, think about writing a new personal statement now to explain your interest in the course and your strengths".
Lewis was overwhelmed by the sixties — by changing styles and changing subjects, by the irony, politics, sarcasm, camp, and verbal humor of Groucho Marxist ideology — and didn't direct any movies released between 1970 and 1981.
I was changing subjects every other day in an attempt to answer those questions.
"Many academics have stayed in the same subject, and I think that I have been restricting my options [by changing subjects too often]." Changing projects gives you many skills, but "the problem is convincing people of that".
