Changing candlestick parts

greetings,

i am not really new to forex but i am not experienced either. when i started about 1 year ago with this first thing i did was following the course of candle sticks by steve nison. it provided me with alot of information about candle sticks which gave me confidence to start investing my time and my money. unfortunately i have made alot of losses because of i am not patient nor expirienced in an advanced way.

but after backtesting my strategy with psar and candlestick readouts , i have found out that its quite profitable over time between periods of january 2013 and till today. to be quite sure i have tested my strategy on older periods of times aswel. it seems that back in the old days ( 2008-20011) charts are showing quite different statistics and the candle stick readouts are not working well infact they are quite bad.

as example
seeing a doji or a spinning top in a uptrend back in 2008 would mostly result in a loss while in present day it will result in some profit in 1d charts

so this made me wonder why there is such difference in patterns from back then and know. what could have made the difference that caused the candlesticks to act differently? and what could cause the same thing in the future.

thank you!