Updating information: I have found that changing my Windows keyboard setting to English-US corrects the issue. I normally leave my keyboard in English - International in order to be able to use accent marks for other languages, and the issue of the cursor jumping back one space seems related to this setting. I can also mitigate the issue while my keyboard setting remains English-International by hitting the space bar after typing the apostrophe, thus "forcing" it to appear as an apostrophe rather potentially an accent mark (which depends on the character typed after the apostrophe key is pressed).

I have also now seen the same behavior using quotation mark, and the same workarounds described above work for it. I wonder if this is due to a fix to some of the other reported accenting issues in Studio, so it may be a feature rather than a bug (for some, anyway).

Hi James McMillan 

Yes the sneaky cursor that jumps. There have been fixes and reviews done for 2022 that help improve the overall Editor UX and stability.
This is one area that was tested but that is for 2022 and you are on 2021.

Historically the mode in which you opened the Editor view seemed to make a difference for some. Example Review mode. 
Alternatively playing with AutoCorrect settings, but that could be specific to user case. 

Do you have access to 2022 all be it for trail purposes to see if your specific use case was addressed?

Lyds

I have the same issue in Trados Studio 2022. I use the features of the US International keyboard all the time, so if there is any fix that doesn't involve switching keyboards, I would love to know about it.

I've got the same problem and haven't found any working fix for it.