I'm a beginner guitarist and I have an acoustic guitar that's 5 years old. It hasn't been restringed in a while. I heard you should use light gauges with old guitars, but how old is old? I just don't want to break my guitar. I also heard that when restringing you should use the same gauge your guitar already has and if you don't, you'll need to get your guitar up by a technican. Is that true? How will different gauges affect my guitar?
5 yrs old isn't old for a guitar - electric, acoustic or classical. 50 yrs old is getting there!
It is more dependant on where it's been kept, how it's been looked after and what sort of bridge it has. If the strings go straight into the body top after going over the bridge, there's a slight concern that new strings (of whatever gauge) may cause the bridge assembly to lift or even rip off. But, if all that looks solid, the same gauge or lighter strings will most likely be o.k.
Re-stringing with different gauge strings strictly speaking will mean the saddles on the bridge will be out of place, but on the assumption that it won't be played much above the 5th fret, intonation problems won't make themselves too obvious - it'll still be pretty well in tune.
Heavier strings will make it sound more beefy than light strings, but it will be more of a battle to play. May be worth taking it in to a luthier or guitar shop and getting a second opinion though.