We're sorry you''re having issues using Photoshop. HiDPI support on Windows is enabled by default, but you can revert to the pre-HiDPI support look by:
- Choose Edit > Preferences > Interface.
- In the Text section, find the UI Scaling drop-down box.
- Select "100%"
- Restart Photoshop
Let us know if that helps.
If you've used Photoshop before, you know that Photoshop has multiple ways to scroll; you can use the scroll bars or the Hand tool. Are you saying neither of those are working?
The suggestion in the other post to look for a UI Scaling preference probably won't help you, because that advice is for Windows and you're using a Mac. However, Photoshop might be affected if you changed the Resolution setting in the Displays preference in the System Preferences on your Mac; do you know if that's been changed since you got your new Mac?
One more idea: If you haven't used Photoshop in a while, you're probably getting used to how Photoshop looks now. Are you not seeing the scroll bar you want? The default appearance, which is dark with low contrast scroll bars, might make it hard to see the document scroll bar; look harder for it and make sure to distinguish it from the scroll bars of panels that are open.