Recent destinations....
On most models now, when you go to the recent destinations list, there is a button at the bottom to delete them. But I seem to remember that was added after customer suggestions, so it might not be there on your old model.
The other way to delete them is to delete the file called MapSettings.cfg which you will find inside the folder for your map (the folder will be called something like "Great_Britain and Ireland", "Australia" or "North America" depending on your particular maps.
You will also lose your "Home" location and any POI warnings you had set up, so you'll have to re-do those.
You can do the above by using Windows Explorer.If you need help on how to achieve that, just ask.
EDIT : I should have reminded you to make a full BACKUP first. This is really important, and can save a LOT of problems later on, so do it before you do anything else.
See here for details:
How to backup the contents of your unit to the computer
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Updating maps and software...
First thing to do is find out what software and maps you are running at the moment and post your results here.
Here's a link to an article on how to do that:
How to find the version numbers of your maps and software
To add new maps and to update software you need to use TomTom "Home", which you can download from
here.
You MUST update the software first, before you try to buy a new map.
To do that, normally you would use "Home 2" (download using the Blue buttons on that webpage, the left-hand one for Windows, right-hand one for Mac), but if your software is VERY old, you may need to start off by using "Home" v1 which has a little download link underneath the main ones. You update the software as far as you can using Home 1 and then install Home 2 and carry on from there.
But take it a step t a time... tell us what software and maps you have now, and we can be a bit more specific about what to do next.