Hi Alide Folz

Apologies if I dont fully understand your request for help but let me try clarify what I can pickup on.

I will break my reply in sections.

1. Working with a TM. 

1A. 100% matches

You translate a segment and it get stored in your TM.
If you revisit this segment or have a duplicate of it - it will show as 100% because the exact same source is obtained from your TM.

1B. CM Matches

A context match is better than a 100% match. To be a context match, the TM segment must be a 100% match to the file segment and the two segments must have the same file context. For the file segment and the TM segment to have the same context, they must both have been preceded by the same segment.

Contextual placement of a segment that contributes to something being CM can be found on the far right hand side of your editor view:

1C: PM

A PerfectMatch is a form of context match that compares updated source files to a corresponding set of existing bilingual files rather than to a TM. It is a method that is used when comparing 2 versions of the same source file. 

Summary: During translation I forsee you getting lots of 100% matches or less, as well as CM matches throughout your documents. Perfect Matches less so unless you purposefully apply PM as part of your work process. More information about TM Matches can be found here: https://docs.sdl.com/783545/577385/sdl-trados-studio/tm-matches as well as TM's in general: https://docs.sdl.com/783545/535398/sdl-trados-studio/translating-with-translation-memories--tms-

2: Merging of Segments

Perhaps this document reference and short video will help: https://docs.sdl.com/813470/662045/trados-studio-2021-sr1/merging-segments

I hope this reply was of help to you

Lydia