Layout of photo gallery changed by itself

[are21]

The layout of my photo gallery on my samsung gallery s4 phone has changed by itself.
when I used to open a folder it would show the normal layout of all the pictures but now when I open any folder, the pictures are enlarged, shown one by one underneath each other. How could this have happened and how can I change this?

Sorry if im posting in the wrong place.

 

[alexcolka]

Exactly there, swipe left and you will see two picture columns again.

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