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.
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
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The "Save" button appears above the "Save as" menu, which is not in your screenshot.