How to Replace All within selected COLUMN of text?

Hello!

Been puzzling over this for a while, trying to work it out, but Word is refusing to let me Replace All within a column of text - it just reverts to the horizontal selection.

I need to replace 1000 lines of colons by a full stop, and if there's any way I can avoid doing that by hand I will certainly take it! Can anyone tell me what the matter is here?

Thanks

When you say "a column of text" is this a column within a table, or a column where the section has been formatted to have multiple columns? At what point does it revert to a horizontal selection? I would think that it would be straightforward to select the 1000 lines you want to change but maybe I'm not understanding what you're describing.

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Attachment 693440
Attachment 693441

Thanks for your response!
I'm trying to replace parts of a subtitle file which is in the wrong format.
There are two sections within each line which need altering (outlined in the first image), hence the need to select each part in separate columns (Alt+drag).
It reverts to the horizontal selection as soon as I've pressed Replace All - I hope this is visible in the second image.

I've just realised Word does not let me paste over a selected column of text to replace it, either. This is very frustrating!

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