First of i no understand how crypto works very well but long time supporter of bitcoin..

What i am stuggling getting my head round is how can the amount of coins to be mined be changed?
for example I thought there was a cap on the amount of coins written in the script, like 21million for btc and 100 billion for doge, but after some reading up on doge it appears there are going to be 5billion per year once the cap is reached? how can this be changed? does this mean crypto currencies can be mined more than origanly stated? or is it just doge, doesnt it make it kind of dodgy, who gets to say how many more can be mined? i always thought no one can control crypto currencies, or is doge just different or a scam?