Definition of 'Work with Change'

Work on Shabbat with a change is exempt. What is the definition of change: a change in relation to the general conduct of the world or a change in relation to the person performing the work personally? Someone who needs to go out on the street with a medical device on Shabbat, and he carries it with a change, but with that change, he walks all week. In the discussed example, he hangs the device on a ring on his suspenders. People on the street do not walk like that, but he walks like that all week. Is this considered a change or not?

I am copying an answer I sent a few weeks ago on this question:

If for this specific device, this is the usual way to carry it out, then regarding the device, it is not a change, but carrying it out in the usual manner.

For example, most objects that a person hangs on belt loops would be considered carrying with a change. But if he hangs a keychain there, it is considered carrying in the usual manner.