One way is to make the size of the redo logs bigger and another way is to do some less work :)
Changing Redo Log File SizesEach Redo Log File member in a Group must be identical in size. If you need to make your Redo Log Files larger, use the following steps.
1. Use the V$LOG view to identify the current active Redo Log Group.
SQL> SELECT group#, status FROM v$log;
2. Drop one or more of the inactive Redo Log Groups keeping at least two current On-line Redo Log Groups.
3. Use operating system commands to delete the files that stored the dropped Redo Log Files.
4. Recreate the groups with larger file sizes. Continue this sequence until all groups have been resized.
Never change underscore parameters without first opening a Service Request (SR) with MyOracleSupport and having a support analyst instruct you to do so.
My recommendation is that you immediately undo what you did.
Then do what you should have done ... increase the size of your redo logs.
I don't say this to be harsh but what you did, both the actions and the way you went about it, marks you as a very dangerous person. Please do yourself, your employer, and your coworkers a huge favor and take an Oracle class and learn how to properly, and conservatively, manage a database.