Hey Jesus Torres del Rey 

There is this article and often such issues are solved thereafter: https://gateway.sdl.com/apex/communityknowledge?articleName=000002461

As the advice can be complex, please feel free to log a case as I believe your issue should be covered due to in proper default functionality / installation related.
If you don't know how to log a case for this, please review this: https://gateway.sdl.com/apex/communityknowledge?articleName=000002535

Have a good day

Lyds

Thank you. I fixed it.

I followed Solution 2 of your KnowledgeBase article. I used the English Operating Sytem file, which works with Windows for the Spanish for Spain locale. I have Windows 10.

However, after doing all the above, and double clicking an SDLTB file, I got the message below. I realised that an old file association was still in place. I am attaching the screenshot:

What I did is I went to the registry again, searched for "Multiterm15", and when I got a hit, I replaced the above path and used my actual Multiterm 2022 (Multiterm17) path instead, leaving the end parameters (/tb "%1") untouched ("C:\Program Files (x86)\Trados\MultiTerm\MultiTerm17\MultiTerm.exe" /tb "%1"). The registry hit actually was the open command for SDL Multiterm files.

It now works.

Best,

Jesús

Jesus Torres del Rey thank you for letting me know that the article was of help.