Hi. I have some information for owners of Samsung Galaxy A12 & are having trouble with taking screenshots.
I've tried it on my new Samsung A12 phone & it works. The way you do it is:-
Select Settings.
Select Accessibility.
Select Interaction & Dexterity.
Go to Assistant Menu & switch the toggle on. This menu should bring up a number of options, & screenshot is among them. After selecting Assistant Menu, you need to scroll down to an option called an Edge Icon which needs to be switched off.
A circle with 4 squares appears on the screen, which you can put your thumb on & move to a suitable place on the screen. Then when you come to needing it to take a screenshot, you simply press the symbol. Far less fiddly than the options of pressing Start & Volume keys, as has been recommended.
The symbol for screenshots should not be affected by clearing history, cache or turning your phone off for the night - it should be there whenever you come to use the phone again. Hope this helps.