When i look solution of editorial i make sure that i understand them correctly. But may times i fail to solve problems using similar idea or even sometimes the same problem. How should i improve my way of practicing to not forget them ?
Also is it good idea to give lot of contests and upsolve them or i should limit the number of contests i give and practice problems from problemset above my rating ?
This might indicate that you are seeing the editorial too fast. If you put in the effort to solve the original problem for a while before seeing the editorial, then chances of forgetting the idea gets minimized because you attach the memory of the effort you spent to come up with it to the idea itself.
You need to revisit every the problem you upsolved after a week or so, then you must just mindsolve it to the point that only the implementation part is left which you might have already done while upsolving. Key is mindsolving, it will help you visualize things better, retain ideas and also make you faster. Atleast it works for me.