After much searching this is clear as mud. I am a US citizen with 2 entries on a 2 month tourist visa. Half way through my 4 month trip I need to cross the border to "activate" entry No. 2. I plan to be in the Kanchanaburi area at that time but am confused by conflicting information. My questions are as follows -

do I need to get a Myanmar visa ahead of time in Bangkok for the crossing near Kanchanaburi?

Can I use the border at 3 pagodas to activate my second Thai tourist visa entry?

Would I need a Myanmar visa ahead of time to activate my 2nd Thai tourist visa at Ranong?

Thanks for any clarifications.

There are only 3 crossings to Myanmar that do not require a visa. The are at Mae Sot, Mae Sai and Ranong.

If you use the Ranong crossing you may be asked to show 20k baht and/or a ticket out of the country. It is not a good crossing to use.