Moving forward, should you wish to continue to operation of this Charity, may I suggest you look into acquiring some online tools to help with documenting transactions?

For example, it would benefit anyone authorized to make purchases to have an app on their smart phone that enables them to take a photo at the time of purchase that is stored in a dedicated filing system-specific to their task.

Examples can be seen in this search engine link:

https://www.bing.com/search?q=app+to+scan+receipts&qs=LT&pq=app+to+scan+&sk=LT3&sc=8-12&cvid=E133A4E759FE4B24976E672F315715F0&FORM=QBLH&sp=4

This is especially effective for use with thermal paper receipts. 

And, there are also effective tools for your smart phone's camera to capture the actual text contained on a surface you are photographing.

https://www.bing.com/search?q=app+to+scan+text+from+image&qs=UT&pq=app+to+scan+text&sc=8-16&cvid=08AEF106B17748D4987D9C03BBD7F6A1&FORM=QBRE&sp=1

If you are an Android Device user, I find APK PURE https://apkpure.com/ to be a very effective tool to search for new apps and upgrade apps already installed (as well as already installed system apps (think Gmail, Youtube, Chrome as examples of system files that may not get updated as often).