I read that when you arrive in Thailand you receive 30 days for free but I have also paid for 60 day tourist visa.

 W

hich visa will they accept first when I arrive in the country?

The 30 day visa exempt, issued on arrival (which is available to certain countries) is for those without a tourist Visa.

 

If you have a valid tourist Visa, that's what will be used.

If i leave and then come back can i then receive the 30 day free visa? 

NOT if you have a valid visa in your passport, as already stated.

32 minutes ago, Erm201 said:

If i leave and then come back can i then receive the 30 day free visa? 

• Yes you can, but you don't get a visa. You get permission to stay for 30 days because you are exempt from needing a visa assuming you're from a qualifying country. 
• If you enter under visa exemption by land you'll get 15 days unless you're from a G7 country in which case you'd get 30. You'd get 30 arriving by air.

you could enter the first time on the 30 day visa exempt, then depending on when you first got that SETV visa which I think you have 90 days to start using since you first got it, you could then come in the second time and enter on that?  I would think you want to use the tourist visa at some point since you paid for it.

4 minutes ago, gk10002000 said:

you could enter the first time on the 30 day visa exempt, then depending on when you first got that SETV visa which I think you have 90 days to start using since you first got it, you could then come in the second time and enter on that?  I would think you want to use the tourist visa at some point since you paid for it.

• An SETV is valid for 3 months from the date it's issued, not 90 days.
• If you have a valid visa in the passport the IO will use the visa. You won't get the choice to enter under visa exemption and keep the visa for a later entry.