Unfortunately built-in F&R cannot search for highlight colour.
I suggest you edit (manually) your document to put it into “Writer form”, provided your document is saved in native format (.odt).
Define a custom character style (look in the built-in help for “Character Style(s)”) changing only the highlight colour. Give it a name of your convenience such as Highlight.
Track manually all your present highlighting, select the range and Ctrl
+M
to remove the present colour. Without deselecting, apply character style Highlight (this will highlight the range with the newly selected colour).
After that, if you are not satisfied with the highlight colour, you only have to change the colour in Highlight definition and it will instantly be transferred to all sequences marked with the style.
EDIT 1
Please, move your no-answer inside your question (edit it to add the details) because this is not a thread but a Q&A site. The site engine will freely reorder the answers according to its rather obscure relevancy rules and time sequence will be lost. Comments to question or answers do not suffer this behaviour.
Highlight colour is retrieved from the OS (which you did not mention) and LO uses it as is. Nearly all other colours may be changed with Tools
>Options
, LibreOffice
>Application Colors
, but this one.
Consequently do it with your OS preference manager.
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