I have a really simple issue to most - but cannot work out how to fix
whenever i paste or move an object the little guide sqaures are really pale and would like to change the colour as my eyesight isnt the best, so i can see them
Sorry to hear about this experience. I hope the suggestions shared by Doug helped resolve the problem. If not, kindly try resetting Illustrator's preferences by following the steps shared in this article (https://helpx.adobe.com/illustrator/kb/troubleshoot-preference-issues.html) and sharing your observations. Disclaimer: Please note that resetting preferences will remove all custom settings, and Illustrator will launch with the defaults. You may take a backup of these settings from the location mentioned in the article.