How to add a character to end of file extension

[Ronstang]

I need to deactivate about 1000 SRT files so I can run all the MKV files through a program to extract all available subtitle streams and the easiest way is to simply add a 1 to the end of the extension. so I need to change:
A Place for Lovers.srt

to

A Place for Lovers.srt1

I'm not sure if it affects the renaming but some of the files have language identifiers in the file name like:

Bananas.eng.srt

But the language identifiers can also be "en" or "es" or "spa".

I would also like to know how to remove the 1 from the end to once again activate the file once I batch process the entire directory.

Thanks

[Luuk]

Greetings Ronstang.
Can use a Filters(12) "Mask" like *.srt then click any folder to present the .srt-files.
So then Extensions(11) would use the "Fixed" drop-down, with text looking like srt1.
There is many other ways, but this is probably the easiest, and doesnt need any dangerous settings.

[Ronstang]

Thanks Luuk.....while that works it isn't any easier than doing it manually. I have almost 1000 directories to make this change in and if I select the directories then every single file in the directory is changed and that won't work. Is there any way to isolate only the SRT files in all the directories like I do in File Explorer so it only applies to them?

[Ronstang]

I figured it out Luuk.....I just selected the parent directory in the left window which showed all the files in all the sub directories....then added a column for "type" in the right window.....then grouped the files by "type"....selected all the SRT files and applied the change. It will be easy to go back when my operation finishes in the morning.

Thanks as always!!

[Luuk]

Sorry for not replying earlier, but as long as the Filters(12) "Mask" is *.srt, then clicking onto any folder will only present your .srt-files.
It doesnt matter if its just 1-folder, or all sub-folders with using a checkmark inside of "Subfolders", it still only presents the .srt-files.
But for me, the best solution is usually just whatever is the easiset to conduct.. Glad you found a solution!

[Ronstang]

Thanks for the info Luuk....it's appreciated. I learn a little bit all the time and occasionally I can figure out how to do something simple without bugging anyone