9e7742db_ime_manipulation___Heroes_Wiki__Theory
[Citations] Future Hiro traveled back to talk to Peter to tell him what to do to save Claire. (Hiros) He must have figured that Peter, who could copy his power, would remain immune to the affects of any paradox Future Hiro caused by going back in time to deliver the warning. Hiro's memories of what the explosion future was like before he went to talk to Peter remained unchanged, though some details about the past did change. (Five Years Gone) [Notes] + This would explain why Future Hiro needed to find an exact point to talk to Peter, before they "met for the first time" in the Dark Future. + It would also explain why he chose Peter - who he knew would gain his power and become similarly immune to the effects of paradox. + It would also explain why Sylar, disguised as Nathan, would be so insistent on killing Hiro - especially after it was confirmed to him that Hiro could travel through time. [Theory] 
A person with the power of space-time manipulation cannot have their memories altered by a change in their own personal timeline. In short, they are immune to the effects of a paradox changing time and if a person changes the past, their own memories of what things were like before the change will remain unaltered. The one exception to this is if they die in another time.
Theory:Space-time manipulation - Heroes Wiki
Theory