3.1 when inflation rate in Thailand higher than other country, price of Goods is increase but when compare with Goods in other country, it seem to be cheaper. That affect to more import. When the import is rise, therefore it is necessary to buy a foreign currency that affect to foreign currency higher. Which you need to use more money for exchanging or it called depreciate of Baht.
3.2 The investor will borrow money from the country that lower interest rate, that is Thailand to invest in country that high interest rate to get profit from the difference in interest rates. That make foreign currency tend to appreciating or depreciation of Baht.
3.3 When GDP of Thailand is high growing, the central bank will increase interest rate to coping with the inflation that make foreign investor want to invest in Thailand. Which they need to buy Baht currency for investment that lead to appreciation of Baht.