If you subscribe to the Photographers Plan you get Photoshop CC2017/2018 plus Lightroom plus any upgrades and you can install them on two computers and they are optimised for high resolution displays. The cost is around $10 a month.
I've just bought a Dell 27 inch table top computer. On my Photoshop CS5, I cannot make the font sizes of the top function and the side function bars bigger. Can somebody help? Thank you.
I'll add my two cents worth just for the heck of it.
So what is the resolution of your new Dell 27 inch screen? If it is QHD 2560 x 1440 pixels, then a 27 inch screen will probably be OK. I recently bought a 32 inch screen with that resolution, and it is fine even with my less than stellar vision. It's when you go to Ultra HD with a 3840 x 2160 pixel resolution that you run into trouble wit older versions of Photoshop. Simply put, you would have made a poor decision through lack of research, and now have no recourse other than to update to Photoshop CC which can switch to a 200% UI, or change the monitor. I don't know where you fit into that.