The Likely field (database field name is amount if you have amended the label) has behaviour hard coded into Access CRM and there will already be a field storing the value you require, this will be in studio as the field name _usdollar, and this will always store the value in the home currency of your system. It is however possible to mimic the home currency value into a custom field and report on that. To do this you will need to do the following (can only be performed by an administrator)
Create a new field in studio and set the following criteria
Data Type = Decimal
Display Label = Something recognisable (e.g. Likely HC)
Precision = 2 (This is decimal places, if you work to more than 2 then change as appropriate)
Check the Calculated Value box
Formula = divide($amount,related($currencies,"conversion_rate"))
Obviously it is up to you as a company if you choose to include this field on your record layout, however it does not need to be on your record layout to include it within a report.
All records will have to have their values recalculated before the value will show.