You have to know that the changes you make end up in the database on osm.org. From there other sites make copies of that data. Some sites do it on a daily basis, others monthly, and well others only took the copy once.
So depending on which site you are looking at, the data can be up-to-date or very outdated.

Another factor is that not all data is visible on all maps. So when you add for example a maxspeed tag to a road, you will never see this on osm.org. This is also true for certain types of POIs.

Also keep in mind that for some smartphone apps, it’s up to you to download a new version of the “map”.