This issue generally happens while fill-up forms
..right way to fix it
update Meta in the header file
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no, maximum-scale=1, user-scalable=0"/>
related article: https://stackoverflow.com/questions/2989263/disable-auto-zoom-in-input-text-tag-safari-on-iphone