Translation segments not overwritten?

Question

I'm used to working with other CAT tools, but I'm currently working in an institution that uses Trados Studio. I've just come across some behaviour that I find astonishing, and I'm wondering if there's something wrong with my settings, as I'm pretty sure it can't be by design. 
 In the screenshot, row 177 is a fuzzy match with row 174. Trados has inserted my translation of row 174, but what it has inserted, and what appears in the TM hits, is the first translation I did, before I made some changes. I assumed that when I edit a row, Trados would overwrite the original version (as occurs in other CAT tools). But it doesn't. In fact, it doesn't even write my new translation. Only my first draft is stored in the TM. Fortunately this occurred where two rows appear close together, but if this happened elsewhere, where the two rows are not so close together, I might have inconsistencies in my text. 
 Is this behaviour normal? Anyone know how to prevent it?

Paul Filkin · Answer

Timothy Barton 
 This might be elated to the use of lookahead which caches three segments ahead to make the lookup faster... especially when working with machine translation. The downside of this approach is that even though you changed the entry you will still see the cached result when the segments are so close to each other. 
 Try turning off lookahead and see if this results in the same behaviour for you:

Paul Filkin · Answer

Timothy Barton 
 Timothy Barton said: Here: docs.sdl.com/.../lookahead-and-the-mt-quota 
 I see what you mean now... although you may have taken it slightly in the wrong way. The advice is simply meant to ensure you don't spend time going over the same document more than once since some MT engines (if you're using MT) charge by the word, or use up free quotas, every time you enter a segment irrespective of whether it's been translated or not. 
 Worth noting however that there are things you can do to ensure this doesn't happen even if you are working with machine translation: 
 
 use the SDL MT Cloud plugin as opposed to the out of the box SDL Language Cloud 
 use a 3rd party MT Provider that has an option not to resend the segments: 
 use a 3rd party MT provider that offers a flat fee 
 turn off the option to apply MT to confirmed segments. Not as effective as the first two since these will also apply to draft segments, but still useful: 
 use your own MT... which you do :-) 
 
 I'd also clarify that the way lookahead works is if you start from the top it does this: 
 
 segment #1: returns three segments and caches them 
 segment#2: returns one more segment as you already have the next two cached 
 
 So it basically just stays ahead of you, so it's not as bad as multiplying up the file by three.

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Translation segments not overwritten?