Sound like native speakers
1) when you need to "That's right" and "This is right" than they differ?2) amplification with "That", in sentences like: "I KNOW / THINK WHAT, ....". When you should use that, and when not - example: You know (that) we learn English step by step

Question

Answer

1) 'That's right' is something that is used more commonly than 'This is right'.

2) Here, both are used the same. 'You know we learn English step by step.' = 'You know that we learn English step by step.'

Answer

no difference, just lasy speach.