It can happen to you on the Samsung Galaxy S5 that a zoom function is triggered by repeatedly tapping the screen that shows you the menu or the settings in double size. This zoom function is a special feature available in Android Lollipop, which can be enabled or disabled in a sub-menu. It is useful if you can not see the font on your phone, because you have forget for your glasses. With the zoom feature you can zoom portions of the menus and thus make it readable.
Simply open on your Samsung Galaxy S5 following submenu to activate that feature:
Home Screen --> Menu --> Settings --> Accessibility --> Vision --> magnification gestures
Move the slider above the right from of "Off" to "On" to enable the function or vice versa to disable it. Zooming the display content can then be carried out as follows. Tap anywhere on the screen three times. You can now move the enlarged area with the finger and thus read all stories. To switch off the zoom, tap again three times on the screen.
Now you know how to activate on the Samsung Galaxy S5 the magnification by gesture control or triple tapping the screen.