I learnt that when I want to say "at this time" I should use 这时候。In a video, I saw 这个时候。 I learnt when I want to use a noun I should use 时间 and measure the word for time is 段。 I am confused now. When I want to say "at this time" I should use : 这时候 or 这个时候 maybe 这段时间 Thank you for your help.
这时, 这时候, 这个时候, 就在这时, 在这一瞬间, 此时此刻, etc. means "at this moment".
这段时间, 这段时间里，这个时期，这个期间，etc. means "during this period" or "in the time period".
In many cases, you must refer to the context to understand whether it is a moment or a period. For example (那时),
那时我们家里很穷. During that time my family was very poor. (when I was a boy).
那时我没有多想，赶紧往人多的地方跑。At that moment I could not think too much but ran toward the crowd.