In order to carry out a country change, Google support told me to uninstall the updates of Google Play (which I see as a downgrade, to version 17), to change the country, and let Google Play update itself (back to version 22.4). It worked for the country change, but now Google Play will not propose any update for my apps. It seems that since the downgrade of Google Play, all my apps have been seen as third-party apps, although most of them were installed by Google Play. (I do not think the country change is responsible.)
Now I have all my apps without a link to Google Play. When I open the description of an app in Google Play, Google Play sees it is installed and shows the buttons "uninstall" and "open". But it is not in its list of installed apps, hence it will not carry out updates on these apps.
How can I have Google Play track my apps again?
With one app, I tried to uninstall and reinstall it (both inside Google Play), but it erased its settings and data... Do I have another options than lose my apps data (imagine with Signal...) or keep them without updates?!