Why in my version(157) of C3 there is no possibility of saving the project? At the same time, the friend has such an opportunity.
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If you want to save files directly to disk, you need to download and install the C3 Desktop Build.
construct.net/en/forum/construct-3/general-discussion-7/construct-desktop-build-beta-131317
The "Save" button appears above the "Save as" menu, which is not in your screenshot.