Doesn't look like those are heated...bettas are tropical fish and need water temperatures of 75-80 degrees F. I can't tell how large those are, but if they're 1 gallons they need two 100% water changes weekly.
I would say 25% to 50% two times a week then 100% once a week for both. They both should have a heater as they need a constant temp of 76-80F.
2.5g is the Min on here but some fish do like 1g better and with proper water changes are fine. But I would definatly get a heater. You can get them for around $15 at walmart and will heat a 1g just fine.
Judging by the temperature strip on Amor's it looks like his tank is a nice warm 79F, which is great. Twilight could probably do with warmer water and a little more swimming space, though. Bettas are curious little fish and love space to swim and explore, even if it is only a 1 gal Kritter Keeper.
For a 1 gal, the general rule seems to be 1 50% and 1 100% water change per week.