When you change the parameter, it is changed in Db only so when you re-start the instance again the change will be lost. Need to click on save button and the profile file will be saved and a backup is created at OS level.
Click on Param Name button
If the required param is not in the listed 500 inputs, simply click on the down arrow button at the top of the above screen. Type in the parameter name partially with * before and after the partial name and hit enter. Choose the required param and double click.
Enter the param value and click copy. It will copy and notify you in the status bar "Changes were made". Now click on back arrow on the top and it will ask you to save the profile. Click OK and it will save the profile to OS.
Then it will ask you to change and activate the profile. Click ON and it will save the profile. Now open the profile in notepad and you will see the changes made to the instance profile (DEV_DVEBMGS_CHALAKI in this case)