[Pixelated images]

[Pixelated images]

Hi guys,

 

I’m a complete novice and would greatly appreciate some help. Would anyone have any idea why when I open a png file on my pc, using affinity designer, and try to enlarge it it becomes badly pixelated, but if I open the same file on my wife’s pc it’s fine? I’ve been racking my brain for the past two days and am only getting no where. 
 

Thanks in advance.