How to fix disappearing text when zooming a document

Hi, and welcome to the Apple (user-to-user) Coimmunity!

Re: "Zooming documents : While zooming a document it disappears every time i m enable to read zoomed text"

We do not know what settings you may be using, or anything much about your ways of working with documents.

There are ways available that may help be more in control of using the zoom features.

Wondering if you have tried following Apple Support's guidance about increasing text size and / or zooming in

Eg: Apple support's online article (link below) may have some tips that help you:

Customize the text size and zoom setting on iPhone - Apple Support

Eg: says :

Increase the text size on iPhone

1. Go to Settings  > Display & Brightness.
2. Tap Text Size.
3. Drag the slider left or right to change the text size.

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Make the text bold on iPhone

1. Go to Settings  > Display & Brightness.
2. Turn on Bold Text.

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Magnify the entire iPhone screen with Display Zoom.

1. Go to Settings  > Display & Brightness.
2. Tap Display Zoom, then tap Larger Text.
3. Tap Done, then tap Use Zoomed.

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See also: Zoom in on the iPhone screen

Eg: says:

"You can magnify the entire screen (Full Screen Zoom)

or

magnify only part of the screen with a resizable lens (Window Zoom).

And,

you can use Zoom together with VoiceOver."

You can see the steps to take for these features in the linked article above.

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If you want, you can see how to: Make iPhone text easier to read with accessibility features

Hope something above will help you get back in control of using the zoom feature in just the way you want.

Else: You may want to contact Apple's Accessibility Support Team:

How to contact Apple for accessibility support - Apple Support

or

Apple's Accessibility Support Website

(NB: You can "Get Support" from the link at the bottom of their website:)

Accessibility Support - Official Apple Support

All the best :-)