Previous years isa

when this years ISA finishes can l go back and still trade in it by changing stocks or using money if l leave some in it,if so how is it done.Thanks

The ISA limits iirc are based on deposits into an ISA wrapper each year I believe. What you do with the funds once inside the wrapper is up to you.

Yes you can still use your account as normal. All that happens is that you get another £20,000 deposit limit to use by 5th April 2022. Note that your deposit limit will be reset and you can’t carry over this year’s allowance.