can anyone help with this one? when i open a pdf file it opens in adobe acrobat,no problem

how ever when the wifes on her account on the same pc and tries opening one it opens in m/soft word and its all gibberish/jumbled rubbish, is there a setting or something to alter it so its the same as on mine? because at the moment if she gets any emails in pdf she has to send them to me,then log onto my account so she can read them