If you are planning on using your credit cards in Thailand, it is imperative before you depart, to notify your credit card company of your travel plans.
Many card companies have a method for doing this online.
Thailand is always seen as one of those suspicious destinations for fraud.
If you do NOT inform your credit card company of your travel plans, you have a high chance of your credit card being blocked when you need it most.
Give yourself the peace of mind your credit cards will work while on your trip to Thailand.