I am an old Linux user, and I distinctly remember having typed some odd commands at times, though probably nothing so arcane as a Windows registry key for sure...
Thanks for your tip, I'll have a look here and report back.
roger@lmde64 ~ $ locate Strahinja
/home/roger/.config/Strahinja Markovic
/home/roger/.config/Strahinja Markovic/Sigil.conf
/home/roger/.local/share/data/Strahinja Markovic
/home/roger/.local/share/data/Strahinja Markovic/Sigil
/home/roger/.local/share/data/Strahinja Markovic/Sigil/dictionaries
Found in the first file:
.../...
[find_replace]
find_strings="<p class=\"let\">([A-Z])", font-family:LinuxLibertineOCRegular, " sgc-1"
replace_strings="<p class=\"let\"><span class=\"let1\"><span class=\"let2\">\\1</span></span>", font-family: 'LinuxLibertineOCRegular',
search_mode=20
look_where=10
search_direction=0
.../...
Yep, this way it's easy to remove selectively search and replace strings. Solved.
Thanks again.