Pixilated fonts

Although I'm not a techie, I've had and used Photoshop for about 25 years.

Recently I bought a new Mac and upgraded to High Sierra (if that's relevant).

I'm a pro photog and the other day, as I have done thousands of times before, I transferred my signature from one photograph to another (same physical size, same 300 dpi).  The signature in the new image was pixilated and all text has been since.

It's incredibly frustrating!  I tried different fonts, restarted, did the anti-alias thing, tried smooth, crisp....

I do not believe I changed any setting but I sure can't figure this out and my deadline has come and gone.

Any other suggestions would sure be appreciated.

Thanks.