can anyone please help me - my 2025 Version
Hello and welcome to Seamly2D forum, @Jacquie_Scott-Cross1
I’ve never worked on Mac, so I have no idea of what works and what doesn’t.
I suggest that you download the latest one here and then install it to a new folder separate to your 2025 version and test that it works properly before deleting the 2025 version.
Also check that your patterns convert correctly and update them to the new version before deleting.
Problem I see is she’s asking for an update that runs on BigSur macOS 11… when the current Seamly build with Qt minimun is macOS 13. Theoretically if there’s a Mac user who has Qt 6.8 they could still build the current codebase which should run on Big Sur. But that could change at any time once I start cleaning up some deprecated functions & MACROS where the code will no longer compile with 6.8. And we don’t want to change the CI workflow to backport using qt 6.8.
There’s a release a couple months back that was still built with Qt 6.8, but had some bugs when switching from Qt 6.5 tp 6.8… some of which I only recently addressed in Qt 6.11 builds. Best I can make out this was the last Qt 6.8 build:
While I have a macBook as of yet I have not built on the Mac. I tried but still need to fix some configurations and it just hasn’t been a priority. 
BTW… this has always been an issue I have with Apple… they break things all the time. Be it software or ports / cords. I still use 1 photo application I ran with Windows 3.1 and it still runs on Windows 11.