Why do you think we constantly say اعوذ بالله من الشیطان الرجیم?
And why do you think we say بسم الله الرحمن الرحیم?
We are instructed to start everything in the name of Allah:
Leaving the house, entering the house, entering your car, eating food, starting an exam, beginning a discussion,etc.
And I can tell that were Allah isn't, then Satan is there.
More important that physical matter it is the matter of guidance (هدایه). So basically if you want to be sure when you are reading Quran then always start with Auzubillah & Bismillah, that will help.
Not starting with such means that you can take care of your own entirely and you don't need Allah's blessing... if you think such then it is when Satan can enter.
فَإِذَا قَرَأْتَ الْقُرْآنَ فَاسْتَعِذْ بِاللّهِ مِنَ الشَّيْطَانِ الرَّجِيمِ
So when you recite the Qur'an, [first] seek refuge in Allah from Satan, the expelled [from His mercy].
Considering this: if you are a pious person and say such then Allah will bless and protect you insha'allah. But then if you are not pious and forget about the necessity of Allah's protection... and just read Quran with no cross-checking... and just interpreting as you wish then obviously Satan can and will try to deviate your understanding. Satan can never alter our understanding, although he invite us to کبر (arrogance) to be forgetful of Allah and to think we can understand Quran on our own and that itself is our downfall.